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"""Popular unsupervised clustering algorithms."""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
from sklearn.cluster._affinity_propagation import (
AffinityPropagation,
affinity_propagation,
)
from sklearn.cluster._agglomerative import (
AgglomerativeClustering,
FeatureAgglomeration,
linkage_tree,
ward_tree,
)
from sklearn.cluster._bicluster import SpectralBiclustering, SpectralCoclustering
from sklearn.cluster._birch import Birch
from sklearn.cluster._bisect_k_means import BisectingKMeans
from sklearn.cluster._dbscan import DBSCAN, dbscan
from sklearn.cluster._hdbscan.hdbscan import HDBSCAN
from sklearn.cluster._kmeans import KMeans, MiniBatchKMeans, k_means, kmeans_plusplus
from sklearn.cluster._mean_shift import (
MeanShift,
estimate_bandwidth,
get_bin_seeds,
mean_shift,
)
from sklearn.cluster._optics import (
OPTICS,
cluster_optics_dbscan,
cluster_optics_xi,
compute_optics_graph,
)
from sklearn.cluster._spectral import SpectralClustering, spectral_clustering
__all__ = [
"DBSCAN",
"HDBSCAN",
"OPTICS",
"AffinityPropagation",
"AgglomerativeClustering",
"Birch",
"BisectingKMeans",
"FeatureAgglomeration",
"KMeans",
"MeanShift",
"MiniBatchKMeans",
"SpectralBiclustering",
"SpectralClustering",
"SpectralCoclustering",
"affinity_propagation",
"cluster_optics_dbscan",
"cluster_optics_xi",
"compute_optics_graph",
"dbscan",
"estimate_bandwidth",
"get_bin_seeds",
"k_means",
"kmeans_plusplus",
"linkage_tree",
"mean_shift",
"spectral_clustering",
"ward_tree",
]

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"""Affinity Propagation clustering algorithm."""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
from numbers import Integral, Real
import numpy as np
from sklearn._config import config_context
from sklearn.base import BaseEstimator, ClusterMixin, _fit_context
from sklearn.exceptions import ConvergenceWarning
from sklearn.metrics import euclidean_distances, pairwise_distances_argmin
from sklearn.utils import check_random_state
from sklearn.utils._param_validation import Interval, StrOptions, validate_params
from sklearn.utils.validation import check_is_fitted, validate_data
def _equal_similarities_and_preferences(S, preference):
def all_equal_preferences():
return np.all(preference == preference.flat[0])
def all_equal_similarities():
# Create mask to ignore diagonal of S
mask = np.ones(S.shape, dtype=bool)
np.fill_diagonal(mask, 0)
return np.all(S[mask].flat == S[mask].flat[0])
return all_equal_preferences() and all_equal_similarities()
def _affinity_propagation(
S,
*,
preference,
convergence_iter,
max_iter,
damping,
verbose,
return_n_iter,
random_state,
):
"""Main affinity propagation algorithm."""
n_samples = S.shape[0]
if n_samples == 1 or _equal_similarities_and_preferences(S, preference):
# It makes no sense to run the algorithm in this case, so return 1 or
# n_samples clusters, depending on preferences
warnings.warn(
"All samples have mutually equal similarities. "
"Returning arbitrary cluster center(s)."
)
if preference.flat[0] > S.flat[n_samples - 1]:
return (
(np.arange(n_samples), np.arange(n_samples), 0)
if return_n_iter
else (np.arange(n_samples), np.arange(n_samples))
)
else:
return (
(np.array([0]), np.array([0] * n_samples), 0)
if return_n_iter
else (np.array([0]), np.array([0] * n_samples))
)
# Place preference on the diagonal of S
S.flat[:: (n_samples + 1)] = preference
A = np.zeros((n_samples, n_samples))
R = np.zeros((n_samples, n_samples)) # Initialize messages
# Intermediate results
tmp = np.zeros((n_samples, n_samples))
# Remove degeneracies
S += (
np.finfo(S.dtype).eps * S + np.finfo(S.dtype).tiny * 100
) * random_state.standard_normal(size=(n_samples, n_samples))
# Execute parallel affinity propagation updates
e = np.zeros((n_samples, convergence_iter))
ind = np.arange(n_samples)
for it in range(max_iter):
# tmp = A + S; compute responsibilities
np.add(A, S, tmp)
I = np.argmax(tmp, axis=1)
Y = tmp[ind, I] # np.max(A + S, axis=1)
tmp[ind, I] = -np.inf
Y2 = np.max(tmp, axis=1)
# tmp = Rnew
np.subtract(S, Y[:, None], tmp)
tmp[ind, I] = S[ind, I] - Y2
# Damping
tmp *= 1 - damping
R *= damping
R += tmp
# tmp = Rp; compute availabilities
np.maximum(R, 0, out=tmp)
tmp.flat[:: n_samples + 1] = R.flat[:: n_samples + 1]
# tmp = -Anew
tmp -= np.sum(tmp, axis=0)
dA = np.diag(tmp).copy()
tmp.clip(0, np.inf, tmp)
tmp.flat[:: n_samples + 1] = dA
# Damping
tmp *= 1 - damping
A *= damping
A -= tmp
# Check for convergence
E = (np.diag(A) + np.diag(R)) > 0
e[:, it % convergence_iter] = E
K = np.sum(E, axis=0)
if it >= convergence_iter:
se = np.sum(e, axis=1)
unconverged = np.sum((se == convergence_iter) + (se == 0)) != n_samples
if (not unconverged and (K > 0)) or (it == max_iter):
never_converged = False
if verbose:
print("Converged after %d iterations." % it)
break
else:
never_converged = True
if verbose:
print("Did not converge")
I = np.flatnonzero(E)
K = I.size # Identify exemplars
if K > 0:
if never_converged:
warnings.warn(
(
"Affinity propagation did not converge, this model "
"may return degenerate cluster centers and labels."
),
ConvergenceWarning,
)
c = np.argmax(S[:, I], axis=1)
c[I] = np.arange(K) # Identify clusters
# Refine the final set of exemplars and clusters and return results
for k in range(K):
ii = np.asarray(c == k).nonzero()[0]
j = np.argmax(np.sum(S[ii[:, np.newaxis], ii], axis=0))
I[k] = ii[j]
c = np.argmax(S[:, I], axis=1)
c[I] = np.arange(K)
labels = I[c]
# Reduce labels to a sorted, gapless, list
cluster_centers_indices = np.unique(labels)
labels = np.searchsorted(cluster_centers_indices, labels)
else:
warnings.warn(
(
"Affinity propagation did not converge and this model "
"will not have any cluster centers."
),
ConvergenceWarning,
)
labels = np.array([-1] * n_samples)
cluster_centers_indices = []
if return_n_iter:
return cluster_centers_indices, labels, it + 1
else:
return cluster_centers_indices, labels
###############################################################################
# Public API
@validate_params(
{
"S": ["array-like"],
"return_n_iter": ["boolean"],
},
prefer_skip_nested_validation=False,
)
def affinity_propagation(
S,
*,
preference=None,
convergence_iter=15,
max_iter=200,
damping=0.5,
copy=True,
verbose=False,
return_n_iter=False,
random_state=None,
):
"""Perform Affinity Propagation Clustering of data.
Read more in the :ref:`User Guide <affinity_propagation>`.
Parameters
----------
S : array-like of shape (n_samples, n_samples)
Matrix of similarities between points.
preference : array-like of shape (n_samples,) or float, default=None
Preferences for each point - points with larger values of
preferences are more likely to be chosen as exemplars. The number of
exemplars, i.e. of clusters, is influenced by the input preferences
value. If the preferences are not passed as arguments, they will be
set to the median of the input similarities (resulting in a moderate
number of clusters). For a smaller amount of clusters, this can be set
to the minimum value of the similarities.
convergence_iter : int, default=15
Number of iterations with no change in the number
of estimated clusters that stops the convergence.
max_iter : int, default=200
Maximum number of iterations.
damping : float, default=0.5
Damping factor between 0.5 and 1.
copy : bool, default=True
If copy is False, the affinity matrix is modified inplace by the
algorithm, for memory efficiency.
verbose : bool, default=False
The verbosity level.
return_n_iter : bool, default=False
Whether or not to return the number of iterations.
random_state : int, RandomState instance or None, default=None
Pseudo-random number generator to control the starting state.
Use an int for reproducible results across function calls.
See the :term:`Glossary <random_state>`.
.. versionadded:: 0.23
this parameter was previously hardcoded as 0.
Returns
-------
cluster_centers_indices : ndarray of shape (n_clusters,)
Index of clusters centers.
labels : ndarray of shape (n_samples,)
Cluster labels for each point.
n_iter : int
Number of iterations run. Returned only if `return_n_iter` is
set to True.
Notes
-----
For an example usage,
see :ref:`sphx_glr_auto_examples_cluster_plot_affinity_propagation.py`.
You may also check out,
:ref:`sphx_glr_auto_examples_applications_plot_stock_market.py`
When the algorithm does not converge, it will still return an array of
``cluster_center_indices`` and labels if there are any exemplars/clusters,
however they may be degenerate and should be used with caution.
When all training samples have equal similarities and equal preferences,
the assignment of cluster centers and labels depends on the preference.
If the preference is smaller than the similarities, a single cluster center
and label ``0`` for every sample will be returned. Otherwise, every
training sample becomes its own cluster center and is assigned a unique
label.
References
----------
Brendan J. Frey and Delbert Dueck, "Clustering by Passing Messages
Between Data Points", Science Feb. 2007
Examples
--------
>>> import numpy as np
>>> from sklearn.cluster import affinity_propagation
>>> from sklearn.metrics.pairwise import euclidean_distances
>>> X = np.array([[1, 2], [1, 4], [1, 0],
... [4, 2], [4, 4], [4, 0]])
>>> S = -euclidean_distances(X, squared=True)
>>> cluster_centers_indices, labels = affinity_propagation(S, random_state=0)
>>> cluster_centers_indices
array([0, 3])
>>> labels
array([0, 0, 0, 1, 1, 1])
"""
estimator = AffinityPropagation(
damping=damping,
max_iter=max_iter,
convergence_iter=convergence_iter,
copy=copy,
preference=preference,
affinity="precomputed",
verbose=verbose,
random_state=random_state,
).fit(S)
if return_n_iter:
return estimator.cluster_centers_indices_, estimator.labels_, estimator.n_iter_
return estimator.cluster_centers_indices_, estimator.labels_
class AffinityPropagation(ClusterMixin, BaseEstimator):
"""Perform Affinity Propagation Clustering of data.
Read more in the :ref:`User Guide <affinity_propagation>`.
Parameters
----------
damping : float, default=0.5
Damping factor in the range `[0.5, 1.0)` is the extent to
which the current value is maintained relative to
incoming values (weighted 1 - damping). This in order
to avoid numerical oscillations when updating these
values (messages).
max_iter : int, default=200
Maximum number of iterations.
convergence_iter : int, default=15
Number of iterations with no change in the number
of estimated clusters that stops the convergence.
copy : bool, default=True
Make a copy of input data.
preference : array-like of shape (n_samples,) or float, default=None
Preferences for each point - points with larger values of
preferences are more likely to be chosen as exemplars. The number
of exemplars, ie of clusters, is influenced by the input
preferences value. If the preferences are not passed as arguments,
they will be set to the median of the input similarities.
affinity : {'euclidean', 'precomputed'}, default='euclidean'
Which affinity to use. At the moment 'precomputed' and
``euclidean`` are supported. 'euclidean' uses the
negative squared euclidean distance between points.
verbose : bool, default=False
Whether to be verbose.
random_state : int, RandomState instance or None, default=None
Pseudo-random number generator to control the starting state.
Use an int for reproducible results across function calls.
See the :term:`Glossary <random_state>`.
.. versionadded:: 0.23
this parameter was previously hardcoded as 0.
Attributes
----------
cluster_centers_indices_ : ndarray of shape (n_clusters,)
Indices of cluster centers.
cluster_centers_ : ndarray of shape (n_clusters, n_features)
Cluster centers (if affinity != ``precomputed``).
labels_ : ndarray of shape (n_samples,)
Labels of each point.
affinity_matrix_ : ndarray of shape (n_samples, n_samples)
Stores the affinity matrix used in ``fit``.
n_iter_ : int
Number of iterations taken to converge.
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
AgglomerativeClustering : Recursively merges the pair of
clusters that minimally increases a given linkage distance.
FeatureAgglomeration : Similar to AgglomerativeClustering,
but recursively merges features instead of samples.
KMeans : K-Means clustering.
MiniBatchKMeans : Mini-Batch K-Means clustering.
MeanShift : Mean shift clustering using a flat kernel.
SpectralClustering : Apply clustering to a projection
of the normalized Laplacian.
Notes
-----
The algorithmic complexity of affinity propagation is quadratic
in the number of points.
When the algorithm does not converge, it will still return an array of
``cluster_center_indices`` and labels if there are any exemplars/clusters,
however they may be degenerate and should be used with caution.
When ``fit`` does not converge, ``cluster_centers_`` is still populated
however it may be degenerate. In such a case, proceed with caution.
If ``fit`` does not converge and fails to produce any ``cluster_centers_``
then ``predict`` will label every sample as ``-1``.
When all training samples have equal similarities and equal preferences,
the assignment of cluster centers and labels depends on the preference.
If the preference is smaller than the similarities, ``fit`` will result in
a single cluster center and label ``0`` for every sample. Otherwise, every
training sample becomes its own cluster center and is assigned a unique
label.
References
----------
Brendan J. Frey and Delbert Dueck, "Clustering by Passing Messages
Between Data Points", Science Feb. 2007
Examples
--------
>>> from sklearn.cluster import AffinityPropagation
>>> import numpy as np
>>> X = np.array([[1, 2], [1, 4], [1, 0],
... [4, 2], [4, 4], [4, 0]])
>>> clustering = AffinityPropagation(random_state=5).fit(X)
>>> clustering
AffinityPropagation(random_state=5)
>>> clustering.labels_
array([0, 0, 0, 1, 1, 1])
>>> clustering.predict([[0, 0], [4, 4]])
array([0, 1])
>>> clustering.cluster_centers_
array([[1, 2],
[4, 2]])
For an example usage,
see :ref:`sphx_glr_auto_examples_cluster_plot_affinity_propagation.py`.
For a comparison of Affinity Propagation with other clustering algorithms, see
:ref:`sphx_glr_auto_examples_cluster_plot_cluster_comparison.py`
"""
_parameter_constraints: dict = {
"damping": [Interval(Real, 0.5, 1.0, closed="left")],
"max_iter": [Interval(Integral, 1, None, closed="left")],
"convergence_iter": [Interval(Integral, 1, None, closed="left")],
"copy": ["boolean"],
"preference": [
"array-like",
Interval(Real, None, None, closed="neither"),
None,
],
"affinity": [StrOptions({"euclidean", "precomputed"})],
"verbose": ["verbose"],
"random_state": ["random_state"],
}
def __init__(
self,
*,
damping=0.5,
max_iter=200,
convergence_iter=15,
copy=True,
preference=None,
affinity="euclidean",
verbose=False,
random_state=None,
):
self.damping = damping
self.max_iter = max_iter
self.convergence_iter = convergence_iter
self.copy = copy
self.verbose = verbose
self.preference = preference
self.affinity = affinity
self.random_state = random_state
def __sklearn_tags__(self):
tags = super().__sklearn_tags__()
tags.input_tags.pairwise = self.affinity == "precomputed"
tags.input_tags.sparse = self.affinity != "precomputed"
return tags
@_fit_context(prefer_skip_nested_validation=True)
def fit(self, X, y=None):
"""Fit the clustering from features, or affinity matrix.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features), or \
array-like of shape (n_samples, n_samples)
Training instances to cluster, or similarities / affinities between
instances if ``affinity='precomputed'``. If a sparse feature matrix
is provided, it will be converted into a sparse ``csr_matrix``.
y : Ignored
Not used, present here for API consistency by convention.
Returns
-------
self
Returns the instance itself.
"""
if self.affinity == "precomputed":
X = validate_data(self, X, copy=self.copy, force_writeable=True)
self.affinity_matrix_ = X
else: # self.affinity == "euclidean"
X = validate_data(self, X, accept_sparse="csr")
self.affinity_matrix_ = -euclidean_distances(X, squared=True)
if self.affinity_matrix_.shape[0] != self.affinity_matrix_.shape[1]:
raise ValueError(
"The matrix of similarities must be a square array. "
f"Got {self.affinity_matrix_.shape} instead."
)
if self.preference is None:
preference = np.median(self.affinity_matrix_)
else:
preference = self.preference
preference = np.asarray(preference)
random_state = check_random_state(self.random_state)
(
self.cluster_centers_indices_,
self.labels_,
self.n_iter_,
) = _affinity_propagation(
self.affinity_matrix_,
max_iter=self.max_iter,
convergence_iter=self.convergence_iter,
preference=preference,
damping=self.damping,
verbose=self.verbose,
return_n_iter=True,
random_state=random_state,
)
if self.affinity != "precomputed":
self.cluster_centers_ = X[self.cluster_centers_indices_].copy()
return self
def predict(self, X):
"""Predict the closest cluster each sample in X belongs to.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
New data to predict. If a sparse matrix is provided, it will be
converted into a sparse ``csr_matrix``.
Returns
-------
labels : ndarray of shape (n_samples,)
Cluster labels.
"""
check_is_fitted(self)
X = validate_data(self, X, reset=False, accept_sparse="csr")
if not hasattr(self, "cluster_centers_"):
raise ValueError(
"Predict method is not supported when affinity='precomputed'."
)
if self.cluster_centers_.shape[0] > 0:
with config_context(assume_finite=True):
return pairwise_distances_argmin(X, self.cluster_centers_)
else:
warnings.warn(
(
"This model does not have any cluster centers "
"because affinity propagation did not converge. "
"Labeling every sample as '-1'."
),
ConvergenceWarning,
)
return np.array([-1] * X.shape[0])
def fit_predict(self, X, y=None):
"""Fit clustering from features/affinity matrix; return cluster labels.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features), or \
array-like of shape (n_samples, n_samples)
Training instances to cluster, or similarities / affinities between
instances if ``affinity='precomputed'``. If a sparse feature matrix
is provided, it will be converted into a sparse ``csr_matrix``.
y : Ignored
Not used, present here for API consistency by convention.
Returns
-------
labels : ndarray of shape (n_samples,)
Cluster labels.
"""
return super().fit_predict(X, y)

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"""Spectral biclustering algorithms."""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
from abc import ABCMeta, abstractmethod
from numbers import Integral
import numpy as np
from scipy.linalg import norm
from scipy.sparse import dia_matrix, issparse
from scipy.sparse.linalg import eigsh, svds
from sklearn.base import BaseEstimator, BiclusterMixin, _fit_context
from sklearn.cluster._kmeans import KMeans, MiniBatchKMeans
from sklearn.utils import check_random_state, check_scalar
from sklearn.utils._param_validation import Interval, StrOptions
from sklearn.utils.extmath import _randomized_svd, make_nonnegative, safe_sparse_dot
from sklearn.utils.validation import assert_all_finite, validate_data
__all__ = ["SpectralBiclustering", "SpectralCoclustering"]
def _scale_normalize(X):
"""Normalize ``X`` by scaling rows and columns independently.
Returns the normalized matrix and the row and column scaling
factors.
"""
X = make_nonnegative(X)
row_diag = np.asarray(1.0 / np.sqrt(X.sum(axis=1))).squeeze()
col_diag = np.asarray(1.0 / np.sqrt(X.sum(axis=0))).squeeze()
row_diag = np.where(np.isnan(row_diag), 0, row_diag)
col_diag = np.where(np.isnan(col_diag), 0, col_diag)
if issparse(X):
n_rows, n_cols = X.shape
r = dia_matrix((row_diag, [0]), shape=(n_rows, n_rows))
c = dia_matrix((col_diag, [0]), shape=(n_cols, n_cols))
an = r @ X @ c
else:
an = row_diag[:, np.newaxis] * X * col_diag
return an, row_diag, col_diag
def _bistochastic_normalize(X, max_iter=1000, tol=1e-5):
"""Normalize rows and columns of ``X`` simultaneously so that all
rows sum to one constant and all columns sum to a different
constant.
"""
# According to paper, this can also be done more efficiently with
# deviation reduction and balancing algorithms.
X = make_nonnegative(X)
X_scaled = X
for _ in range(max_iter):
X_new, _, _ = _scale_normalize(X_scaled)
if issparse(X):
dist = norm(X_scaled.data - X.data)
else:
dist = norm(X_scaled - X_new)
X_scaled = X_new
if dist is not None and dist < tol:
break
return X_scaled
def _log_normalize(X):
"""Normalize ``X`` according to Kluger's log-interactions scheme."""
X = make_nonnegative(X, min_value=1)
if issparse(X):
raise ValueError(
"Cannot compute log of a sparse matrix,"
" because log(x) diverges to -infinity as x"
" goes to 0."
)
L = np.log(X)
row_avg = L.mean(axis=1)[:, np.newaxis]
col_avg = L.mean(axis=0)
avg = L.mean()
return L - row_avg - col_avg + avg
class BaseSpectral(BiclusterMixin, BaseEstimator, metaclass=ABCMeta):
"""Base class for spectral biclustering."""
_parameter_constraints: dict = {
"svd_method": [StrOptions({"randomized", "arpack"})],
"n_svd_vecs": [Interval(Integral, 0, None, closed="left"), None],
"mini_batch": ["boolean"],
"init": [StrOptions({"k-means++", "random"}), np.ndarray],
"n_init": [Interval(Integral, 1, None, closed="left")],
"random_state": ["random_state"],
}
@abstractmethod
def __init__(
self,
n_clusters=3,
svd_method="randomized",
n_svd_vecs=None,
mini_batch=False,
init="k-means++",
n_init=10,
random_state=None,
):
self.n_clusters = n_clusters
self.svd_method = svd_method
self.n_svd_vecs = n_svd_vecs
self.mini_batch = mini_batch
self.init = init
self.n_init = n_init
self.random_state = random_state
@abstractmethod
def _check_parameters(self, n_samples):
"""Validate parameters depending on the input data."""
@_fit_context(prefer_skip_nested_validation=True)
def fit(self, X, y=None):
"""Create a biclustering for X.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Training data.
y : Ignored
Not used, present for API consistency by convention.
Returns
-------
self : object
SpectralBiclustering instance.
"""
X = validate_data(self, X, accept_sparse="csr", dtype=np.float64)
self._check_parameters(X.shape[0])
self._fit(X)
return self
def _svd(self, array, n_components, n_discard):
"""Returns first `n_components` left and right singular
vectors u and v, discarding the first `n_discard`.
"""
if self.svd_method == "randomized":
kwargs = {}
if self.n_svd_vecs is not None:
kwargs["n_oversamples"] = self.n_svd_vecs
u, _, vt = _randomized_svd(
array, n_components, random_state=self.random_state, **kwargs
)
elif self.svd_method == "arpack":
u, _, vt = svds(array, k=n_components, ncv=self.n_svd_vecs)
if np.any(np.isnan(vt)):
# some eigenvalues of A * A.T are negative, causing
# sqrt() to be np.nan. This causes some vectors in vt
# to be np.nan.
A = safe_sparse_dot(array.T, array)
random_state = check_random_state(self.random_state)
# initialize with [-1,1] as in ARPACK
v0 = random_state.uniform(-1, 1, A.shape[0])
_, v = eigsh(A, ncv=self.n_svd_vecs, v0=v0)
vt = v.T
if np.any(np.isnan(u)):
A = safe_sparse_dot(array, array.T)
random_state = check_random_state(self.random_state)
# initialize with [-1,1] as in ARPACK
v0 = random_state.uniform(-1, 1, A.shape[0])
_, u = eigsh(A, ncv=self.n_svd_vecs, v0=v0)
assert_all_finite(u)
assert_all_finite(vt)
u = u[:, n_discard:]
vt = vt[n_discard:]
return u, vt.T
def _k_means(self, data, n_clusters):
if self.mini_batch:
model = MiniBatchKMeans(
n_clusters,
init=self.init,
n_init=self.n_init,
random_state=self.random_state,
)
else:
model = KMeans(
n_clusters,
init=self.init,
n_init=self.n_init,
random_state=self.random_state,
)
model.fit(data)
centroid = model.cluster_centers_
labels = model.labels_
return centroid, labels
def __sklearn_tags__(self):
tags = super().__sklearn_tags__()
tags.input_tags.sparse = True
return tags
class SpectralCoclustering(BaseSpectral):
"""Spectral Co-Clustering algorithm (Dhillon, 2001) [1]_.
Clusters rows and columns of an array `X` to solve the relaxed
normalized cut of the bipartite graph created from `X` as follows:
the edge between row vertex `i` and column vertex `j` has weight
`X[i, j]`.
The resulting bicluster structure is block-diagonal, since each
row and each column belongs to exactly one bicluster.
Supports sparse matrices, as long as they are nonnegative.
Read more in the :ref:`User Guide <spectral_coclustering>`.
Parameters
----------
n_clusters : int, default=3
The number of biclusters to find.
svd_method : {'randomized', 'arpack'}, default='randomized'
Selects the algorithm for finding singular vectors. May be
'randomized' or 'arpack'. If 'randomized', use
:func:`sklearn.utils.extmath.randomized_svd`, which may be faster
for large matrices. If 'arpack', use
:func:`scipy.sparse.linalg.svds`, which is more accurate, but
possibly slower in some cases.
n_svd_vecs : int, default=None
Number of vectors to use in calculating the SVD. Corresponds
to `ncv` when `svd_method=arpack` and `n_oversamples` when
`svd_method` is 'randomized`.
mini_batch : bool, default=False
Whether to use mini-batch k-means, which is faster but may get
different results.
init : {'k-means++', 'random'}, or ndarray of shape \
(n_clusters, n_features), default='k-means++'
Method for initialization of k-means algorithm; defaults to
'k-means++'.
n_init : int, default=10
Number of random initializations that are tried with the
k-means algorithm.
If mini-batch k-means is used, the best initialization is
chosen and the algorithm runs once. Otherwise, the algorithm
is run for each initialization and the best solution chosen.
random_state : int, RandomState instance, default=None
Used for randomizing the singular value decomposition and the k-means
initialization. Use an int to make the randomness deterministic.
See :term:`Glossary <random_state>`.
Attributes
----------
rows_ : array-like of shape (n_row_clusters, n_rows)
Results of the clustering. `rows[i, r]` is True if
cluster `i` contains row `r`. Available only after calling ``fit``.
columns_ : array-like of shape (n_column_clusters, n_columns)
Results of the clustering, like `rows`.
row_labels_ : array-like of shape (n_rows,)
The bicluster label of each row.
column_labels_ : array-like of shape (n_cols,)
The bicluster label of each column.
biclusters_ : tuple of two ndarrays
The tuple contains the `rows_` and `columns_` arrays.
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
SpectralBiclustering : Partitions rows and columns under the assumption
that the data has an underlying checkerboard structure.
References
----------
.. [1] :doi:`Dhillon, Inderjit S, 2001. Co-clustering documents and words using
bipartite spectral graph partitioning.
<10.1145/502512.502550>`
Examples
--------
>>> from sklearn.cluster import SpectralCoclustering
>>> import numpy as np
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> clustering = SpectralCoclustering(n_clusters=2, random_state=0).fit(X)
>>> clustering.row_labels_ #doctest: +SKIP
array([0, 1, 1, 0, 0, 0], dtype=int32)
>>> clustering.column_labels_ #doctest: +SKIP
array([0, 0], dtype=int32)
>>> clustering
SpectralCoclustering(n_clusters=2, random_state=0)
For a more detailed example, see the following:
:ref:`sphx_glr_auto_examples_bicluster_plot_spectral_coclustering.py`.
"""
_parameter_constraints: dict = {
**BaseSpectral._parameter_constraints,
"n_clusters": [Interval(Integral, 1, None, closed="left")],
}
def __init__(
self,
n_clusters=3,
*,
svd_method="randomized",
n_svd_vecs=None,
mini_batch=False,
init="k-means++",
n_init=10,
random_state=None,
):
super().__init__(
n_clusters, svd_method, n_svd_vecs, mini_batch, init, n_init, random_state
)
def _check_parameters(self, n_samples):
if self.n_clusters > n_samples:
raise ValueError(
f"n_clusters should be <= n_samples={n_samples}. Got"
f" {self.n_clusters} instead."
)
def _fit(self, X):
normalized_data, row_diag, col_diag = _scale_normalize(X)
n_sv = 1 + int(np.ceil(np.log2(self.n_clusters)))
u, v = self._svd(normalized_data, n_sv, n_discard=1)
z = np.vstack((row_diag[:, np.newaxis] * u, col_diag[:, np.newaxis] * v))
_, labels = self._k_means(z, self.n_clusters)
n_rows = X.shape[0]
self.row_labels_ = labels[:n_rows]
self.column_labels_ = labels[n_rows:]
self.rows_ = np.vstack([self.row_labels_ == c for c in range(self.n_clusters)])
self.columns_ = np.vstack(
[self.column_labels_ == c for c in range(self.n_clusters)]
)
class SpectralBiclustering(BaseSpectral):
"""Spectral biclustering (Kluger, 2003) [1]_.
Partitions rows and columns under the assumption that the data has
an underlying checkerboard structure. For instance, if there are
two row partitions and three column partitions, each row will
belong to three biclusters, and each column will belong to two
biclusters. The outer product of the corresponding row and column
label vectors gives this checkerboard structure.
Read more in the :ref:`User Guide <spectral_biclustering>`.
Parameters
----------
n_clusters : int or tuple (n_row_clusters, n_column_clusters), default=3
The number of row and column clusters in the checkerboard
structure.
method : {'bistochastic', 'scale', 'log'}, default='bistochastic'
Method of normalizing and converting singular vectors into
biclusters. May be one of 'scale', 'bistochastic', or 'log'.
The authors recommend using 'log'. If the data is sparse,
however, log normalization will not work, which is why the
default is 'bistochastic'.
.. warning::
if `method='log'`, the data must not be sparse.
n_components : int, default=6
Number of singular vectors to check.
n_best : int, default=3
Number of best singular vectors to which to project the data
for clustering.
svd_method : {'randomized', 'arpack'}, default='randomized'
Selects the algorithm for finding singular vectors. May be
'randomized' or 'arpack'. If 'randomized', uses
:func:`~sklearn.utils.extmath.randomized_svd`, which may be faster
for large matrices. If 'arpack', uses
`scipy.sparse.linalg.svds`, which is more accurate, but
possibly slower in some cases.
n_svd_vecs : int, default=None
Number of vectors to use in calculating the SVD. Corresponds
to `ncv` when `svd_method=arpack` and `n_oversamples` when
`svd_method` is 'randomized`.
mini_batch : bool, default=False
Whether to use mini-batch k-means, which is faster but may get
different results.
init : {'k-means++', 'random'} or ndarray of shape (n_clusters, n_features), \
default='k-means++'
Method for initialization of k-means algorithm; defaults to
'k-means++'.
n_init : int, default=10
Number of random initializations that are tried with the
k-means algorithm.
If mini-batch k-means is used, the best initialization is
chosen and the algorithm runs once. Otherwise, the algorithm
is run for each initialization and the best solution chosen.
random_state : int, RandomState instance, default=None
Used for randomizing the singular value decomposition and the k-means
initialization. Use an int to make the randomness deterministic.
See :term:`Glossary <random_state>`.
Attributes
----------
rows_ : array-like of shape (n_row_clusters, n_rows)
Results of the clustering. `rows[i, r]` is True if
cluster `i` contains row `r`. Available only after calling ``fit``.
columns_ : array-like of shape (n_column_clusters, n_columns)
Results of the clustering, like `rows`.
row_labels_ : array-like of shape (n_rows,)
Row partition labels.
column_labels_ : array-like of shape (n_cols,)
Column partition labels.
biclusters_ : tuple of two ndarrays
The tuple contains the `rows_` and `columns_` arrays.
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
SpectralCoclustering : Clusters rows and columns of an array `X` to solve the
relaxed normalized cut of the bipartite graph created from `X`.
References
----------
.. [1] :doi:`Kluger, Yuval, et. al., 2003. Spectral biclustering of microarray
data: coclustering genes and conditions.
<10.1101/gr.648603>`
Examples
--------
>>> from sklearn.cluster import SpectralBiclustering
>>> import numpy as np
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> clustering = SpectralBiclustering(n_clusters=2, random_state=0).fit(X)
>>> clustering.row_labels_
array([1, 1, 1, 0, 0, 0], dtype=int32)
>>> clustering.column_labels_
array([1, 0], dtype=int32)
>>> clustering
SpectralBiclustering(n_clusters=2, random_state=0)
For a more detailed example, see
:ref:`sphx_glr_auto_examples_bicluster_plot_spectral_biclustering.py`
"""
_parameter_constraints: dict = {
**BaseSpectral._parameter_constraints,
"n_clusters": [Interval(Integral, 1, None, closed="left"), tuple],
"method": [StrOptions({"bistochastic", "scale", "log"})],
"n_components": [Interval(Integral, 1, None, closed="left")],
"n_best": [Interval(Integral, 1, None, closed="left")],
}
def __init__(
self,
n_clusters=3,
*,
method="bistochastic",
n_components=6,
n_best=3,
svd_method="randomized",
n_svd_vecs=None,
mini_batch=False,
init="k-means++",
n_init=10,
random_state=None,
):
super().__init__(
n_clusters, svd_method, n_svd_vecs, mini_batch, init, n_init, random_state
)
self.method = method
self.n_components = n_components
self.n_best = n_best
def _check_parameters(self, n_samples):
if isinstance(self.n_clusters, Integral):
if self.n_clusters > n_samples:
raise ValueError(
f"n_clusters should be <= n_samples={n_samples}. Got"
f" {self.n_clusters} instead."
)
else: # tuple
try:
n_row_clusters, n_column_clusters = self.n_clusters
check_scalar(
n_row_clusters,
"n_row_clusters",
target_type=Integral,
min_val=1,
max_val=n_samples,
)
check_scalar(
n_column_clusters,
"n_column_clusters",
target_type=Integral,
min_val=1,
max_val=n_samples,
)
except (ValueError, TypeError) as e:
raise ValueError(
"Incorrect parameter n_clusters has value:"
f" {self.n_clusters}. It should either be a single integer"
" or an iterable with two integers:"
" (n_row_clusters, n_column_clusters)"
" And the values are should be in the"
" range: (1, n_samples)"
) from e
if self.n_best > self.n_components:
raise ValueError(
f"n_best={self.n_best} must be <= n_components={self.n_components}."
)
def _fit(self, X):
n_sv = self.n_components
if self.method == "bistochastic":
normalized_data = _bistochastic_normalize(X)
n_sv += 1
elif self.method == "scale":
normalized_data, _, _ = _scale_normalize(X)
n_sv += 1
elif self.method == "log":
normalized_data = _log_normalize(X)
n_discard = 0 if self.method == "log" else 1
u, v = self._svd(normalized_data, n_sv, n_discard)
ut = u.T
vt = v.T
try:
n_row_clusters, n_col_clusters = self.n_clusters
except TypeError:
n_row_clusters = n_col_clusters = self.n_clusters
best_ut = self._fit_best_piecewise(ut, self.n_best, n_row_clusters)
best_vt = self._fit_best_piecewise(vt, self.n_best, n_col_clusters)
self.row_labels_ = self._project_and_cluster(X, best_vt.T, n_row_clusters)
self.column_labels_ = self._project_and_cluster(X.T, best_ut.T, n_col_clusters)
self.rows_ = np.vstack(
[
self.row_labels_ == label
for label in range(n_row_clusters)
for _ in range(n_col_clusters)
]
)
self.columns_ = np.vstack(
[
self.column_labels_ == label
for _ in range(n_row_clusters)
for label in range(n_col_clusters)
]
)
def _fit_best_piecewise(self, vectors, n_best, n_clusters):
"""Find the ``n_best`` vectors that are best approximated by piecewise
constant vectors.
The piecewise vectors are found by k-means; the best is chosen
according to Euclidean distance.
"""
def make_piecewise(v):
centroid, labels = self._k_means(v.reshape(-1, 1), n_clusters)
return centroid[labels].ravel()
piecewise_vectors = np.apply_along_axis(make_piecewise, axis=1, arr=vectors)
dists = np.apply_along_axis(norm, axis=1, arr=(vectors - piecewise_vectors))
result = vectors[np.argsort(dists)[:n_best]]
return result
def _project_and_cluster(self, data, vectors, n_clusters):
"""Project ``data`` to ``vectors`` and cluster the result."""
projected = safe_sparse_dot(data, vectors)
_, labels = self._k_means(projected, n_clusters)
return labels

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# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
from math import sqrt
from numbers import Integral, Real
import numpy as np
from scipy import sparse
from sklearn._config import config_context
from sklearn.base import (
BaseEstimator,
ClassNamePrefixFeaturesOutMixin,
ClusterMixin,
TransformerMixin,
_fit_context,
)
from sklearn.cluster import AgglomerativeClustering
from sklearn.exceptions import ConvergenceWarning
from sklearn.metrics import pairwise_distances_argmin
from sklearn.metrics.pairwise import euclidean_distances
from sklearn.utils._param_validation import Interval
from sklearn.utils.extmath import row_norms
from sklearn.utils.validation import check_is_fitted, validate_data
def _iterate_sparse_X(X):
"""This little hack returns a densified row when iterating over a sparse
matrix, instead of constructing a sparse matrix for every row that is
expensive.
"""
n_samples = X.shape[0]
X_indices = X.indices
X_data = X.data
X_indptr = X.indptr
for i in range(n_samples):
row = np.zeros(X.shape[1])
startptr, endptr = X_indptr[i], X_indptr[i + 1]
nonzero_indices = X_indices[startptr:endptr]
row[nonzero_indices] = X_data[startptr:endptr]
yield row
def _split_node(node, threshold, branching_factor):
"""The node has to be split if there is no place for a new subcluster
in the node.
1. Two empty nodes and two empty subclusters are initialized.
2. The pair of distant subclusters are found.
3. The properties of the empty subclusters and nodes are updated
according to the nearest distance between the subclusters to the
pair of distant subclusters.
4. The two nodes are set as children to the two subclusters.
"""
new_subcluster1 = _CFSubcluster()
new_subcluster2 = _CFSubcluster()
new_node1 = _CFNode(
threshold=threshold,
branching_factor=branching_factor,
is_leaf=node.is_leaf,
n_features=node.n_features,
dtype=node.init_centroids_.dtype,
)
new_node2 = _CFNode(
threshold=threshold,
branching_factor=branching_factor,
is_leaf=node.is_leaf,
n_features=node.n_features,
dtype=node.init_centroids_.dtype,
)
new_subcluster1.child_ = new_node1
new_subcluster2.child_ = new_node2
if node.is_leaf:
if node.prev_leaf_ is not None:
node.prev_leaf_.next_leaf_ = new_node1
new_node1.prev_leaf_ = node.prev_leaf_
new_node1.next_leaf_ = new_node2
new_node2.prev_leaf_ = new_node1
new_node2.next_leaf_ = node.next_leaf_
if node.next_leaf_ is not None:
node.next_leaf_.prev_leaf_ = new_node2
dist = euclidean_distances(
node.centroids_, Y_norm_squared=node.squared_norm_, squared=True
)
n_clusters = dist.shape[0]
farthest_idx = np.unravel_index(dist.argmax(), (n_clusters, n_clusters))
node1_dist, node2_dist = dist[(farthest_idx,)]
node1_closer = node1_dist < node2_dist
# make sure node1 is closest to itself even if all distances are equal.
# This can only happen when all node.centroids_ are duplicates leading to all
# distances between centroids being zero.
node1_closer[farthest_idx[0]] = True
for idx, subcluster in enumerate(node.subclusters_):
if node1_closer[idx]:
new_node1.append_subcluster(subcluster)
new_subcluster1.update(subcluster)
else:
new_node2.append_subcluster(subcluster)
new_subcluster2.update(subcluster)
return new_subcluster1, new_subcluster2
class _CFNode:
"""Each node in a CFTree is called a CFNode.
The CFNode can have a maximum of branching_factor
number of CFSubclusters.
Parameters
----------
threshold : float
Threshold needed for a new subcluster to enter a CFSubcluster.
branching_factor : int
Maximum number of CF subclusters in each node.
is_leaf : bool
We need to know if the CFNode is a leaf or not, in order to
retrieve the final subclusters.
n_features : int
The number of features.
Attributes
----------
subclusters_ : list
List of subclusters for a particular CFNode.
prev_leaf_ : _CFNode
Useful only if is_leaf is True.
next_leaf_ : _CFNode
next_leaf. Useful only if is_leaf is True.
the final subclusters.
init_centroids_ : ndarray of shape (branching_factor + 1, n_features)
Manipulate ``init_centroids_`` throughout rather than centroids_ since
the centroids are just a view of the ``init_centroids_`` .
init_sq_norm_ : ndarray of shape (branching_factor + 1,)
manipulate init_sq_norm_ throughout. similar to ``init_centroids_``.
centroids_ : ndarray of shape (branching_factor + 1, n_features)
View of ``init_centroids_``.
squared_norm_ : ndarray of shape (branching_factor + 1,)
View of ``init_sq_norm_``.
"""
def __init__(self, *, threshold, branching_factor, is_leaf, n_features, dtype):
self.threshold = threshold
self.branching_factor = branching_factor
self.is_leaf = is_leaf
self.n_features = n_features
# The list of subclusters, centroids and squared norms
# to manipulate throughout.
self.subclusters_ = []
self.init_centroids_ = np.zeros((branching_factor + 1, n_features), dtype=dtype)
self.init_sq_norm_ = np.zeros((branching_factor + 1), dtype)
self.squared_norm_ = []
self.prev_leaf_ = None
self.next_leaf_ = None
def append_subcluster(self, subcluster):
n_samples = len(self.subclusters_)
self.subclusters_.append(subcluster)
self.init_centroids_[n_samples] = subcluster.centroid_
self.init_sq_norm_[n_samples] = subcluster.sq_norm_
# Keep centroids and squared norm as views. In this way
# if we change init_centroids and init_sq_norm_, it is
# sufficient,
self.centroids_ = self.init_centroids_[: n_samples + 1, :]
self.squared_norm_ = self.init_sq_norm_[: n_samples + 1]
def update_split_subclusters(self, subcluster, new_subcluster1, new_subcluster2):
"""Remove a subcluster from a node and update it with the
split subclusters.
"""
ind = self.subclusters_.index(subcluster)
self.subclusters_[ind] = new_subcluster1
self.init_centroids_[ind] = new_subcluster1.centroid_
self.init_sq_norm_[ind] = new_subcluster1.sq_norm_
self.append_subcluster(new_subcluster2)
def insert_cf_subcluster(self, subcluster):
"""Insert a new subcluster into the node."""
if not self.subclusters_:
self.append_subcluster(subcluster)
return False
threshold = self.threshold
branching_factor = self.branching_factor
# We need to find the closest subcluster among all the
# subclusters so that we can insert our new subcluster.
dist_matrix = np.dot(self.centroids_, subcluster.centroid_)
dist_matrix *= -2.0
dist_matrix += self.squared_norm_
closest_index = np.argmin(dist_matrix)
closest_subcluster = self.subclusters_[closest_index]
# If the subcluster has a child, we need a recursive strategy.
if closest_subcluster.child_ is not None:
split_child = closest_subcluster.child_.insert_cf_subcluster(subcluster)
if not split_child:
# If it is determined that the child need not be split, we
# can just update the closest_subcluster
closest_subcluster.update(subcluster)
self.init_centroids_[closest_index] = self.subclusters_[
closest_index
].centroid_
self.init_sq_norm_[closest_index] = self.subclusters_[
closest_index
].sq_norm_
return False
# things not too good. we need to redistribute the subclusters in
# our child node, and add a new subcluster in the parent
# subcluster to accommodate the new child.
else:
new_subcluster1, new_subcluster2 = _split_node(
closest_subcluster.child_,
threshold,
branching_factor,
)
self.update_split_subclusters(
closest_subcluster, new_subcluster1, new_subcluster2
)
if len(self.subclusters_) > self.branching_factor:
return True
return False
# good to go!
else:
merged = closest_subcluster.merge_subcluster(subcluster, self.threshold)
if merged:
self.init_centroids_[closest_index] = closest_subcluster.centroid_
self.init_sq_norm_[closest_index] = closest_subcluster.sq_norm_
return False
# not close to any other subclusters, and we still
# have space, so add.
elif len(self.subclusters_) < self.branching_factor:
self.append_subcluster(subcluster)
return False
# We do not have enough space nor is it closer to an
# other subcluster. We need to split.
else:
self.append_subcluster(subcluster)
return True
class _CFSubcluster:
"""Each subcluster in a CFNode is called a CFSubcluster.
A CFSubcluster can have a CFNode has its child.
Parameters
----------
linear_sum : ndarray of shape (n_features,), default=None
Sample. This is kept optional to allow initialization of empty
subclusters.
Attributes
----------
n_samples_ : int
Number of samples that belong to each subcluster.
linear_sum_ : ndarray
Linear sum of all the samples in a subcluster. Prevents holding
all sample data in memory.
squared_sum_ : float
Sum of the squared l2 norms of all samples belonging to a subcluster.
centroid_ : ndarray of shape (branching_factor + 1, n_features)
Centroid of the subcluster. Prevent recomputing of centroids when
``CFNode.centroids_`` is called.
child_ : _CFNode
Child Node of the subcluster. Once a given _CFNode is set as the child
of the _CFNode, it is set to ``self.child_``.
sq_norm_ : ndarray of shape (branching_factor + 1,)
Squared norm of the subcluster. Used to prevent recomputing when
pairwise minimum distances are computed.
"""
def __init__(self, *, linear_sum=None):
if linear_sum is None:
self.n_samples_ = 0
self.squared_sum_ = 0.0
self.centroid_ = self.linear_sum_ = 0
else:
self.n_samples_ = 1
self.centroid_ = self.linear_sum_ = linear_sum
self.squared_sum_ = self.sq_norm_ = np.dot(
self.linear_sum_, self.linear_sum_
)
self.child_ = None
def update(self, subcluster):
self.n_samples_ += subcluster.n_samples_
self.linear_sum_ += subcluster.linear_sum_
self.squared_sum_ += subcluster.squared_sum_
self.centroid_ = self.linear_sum_ / self.n_samples_
self.sq_norm_ = np.dot(self.centroid_, self.centroid_)
def merge_subcluster(self, nominee_cluster, threshold):
"""Check if a cluster is worthy enough to be merged. If
yes then merge.
"""
new_ss = self.squared_sum_ + nominee_cluster.squared_sum_
new_ls = self.linear_sum_ + nominee_cluster.linear_sum_
new_n = self.n_samples_ + nominee_cluster.n_samples_
new_centroid = (1 / new_n) * new_ls
new_sq_norm = np.dot(new_centroid, new_centroid)
# The squared radius of the cluster is defined:
# r^2 = sum_i ||x_i - c||^2 / n
# with x_i the n points assigned to the cluster and c its centroid:
# c = sum_i x_i / n
# This can be expanded to:
# r^2 = sum_i ||x_i||^2 / n - 2 < sum_i x_i / n, c> + n ||c||^2 / n
# and therefore simplifies to:
# r^2 = sum_i ||x_i||^2 / n - ||c||^2
sq_radius = new_ss / new_n - new_sq_norm
if sq_radius <= threshold**2:
(
self.n_samples_,
self.linear_sum_,
self.squared_sum_,
self.centroid_,
self.sq_norm_,
) = (new_n, new_ls, new_ss, new_centroid, new_sq_norm)
return True
return False
@property
def radius(self):
"""Return radius of the subcluster"""
# Because of numerical issues, this could become negative
sq_radius = self.squared_sum_ / self.n_samples_ - self.sq_norm_
return sqrt(max(0, sq_radius))
class Birch(
ClassNamePrefixFeaturesOutMixin, ClusterMixin, TransformerMixin, BaseEstimator
):
"""Implements the BIRCH clustering algorithm.
It is a memory-efficient, online-learning algorithm provided as an
alternative to :class:`MiniBatchKMeans`. It constructs a tree
data structure with the cluster centroids being read off the leaf.
These can be either the final cluster centroids or can be provided as input
to another clustering algorithm such as :class:`AgglomerativeClustering`.
Read more in the :ref:`User Guide <birch>`.
.. versionadded:: 0.16
Parameters
----------
threshold : float, default=0.5
The radius of the subcluster obtained by merging a new sample and the
closest subcluster should be lesser than the threshold. Otherwise a new
subcluster is started. Setting this value to be very low promotes
splitting and vice-versa.
branching_factor : int, default=50
Maximum number of CF subclusters in each node. If a new samples enters
such that the number of subclusters exceed the branching_factor then
that node is split into two nodes with the subclusters redistributed
in each. The parent subcluster of that node is removed and two new
subclusters are added as parents of the 2 split nodes.
n_clusters : int, instance of sklearn.cluster model or None, default=3
Number of clusters after the final clustering step, which treats the
subclusters from the leaves as new samples.
- `None` : the final clustering step is not performed and the
subclusters are returned as they are.
- :mod:`sklearn.cluster` Estimator : If a model is provided, the model
is fit treating the subclusters as new samples and the initial data
is mapped to the label of the closest subcluster.
- `int` : the model fit is :class:`AgglomerativeClustering` with
`n_clusters` set to be equal to the int.
compute_labels : bool, default=True
Whether or not to compute labels for each fit.
Attributes
----------
root_ : _CFNode
Root of the CFTree.
dummy_leaf_ : _CFNode
Start pointer to all the leaves.
subcluster_centers_ : ndarray
Centroids of all subclusters read directly from the leaves.
subcluster_labels_ : ndarray
Labels assigned to the centroids of the subclusters after
they are clustered globally.
labels_ : ndarray of shape (n_samples,)
Array of labels assigned to the input data.
if partial_fit is used instead of fit, they are assigned to the
last batch of data.
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
MiniBatchKMeans : Alternative implementation that does incremental updates
of the centers' positions using mini-batches.
Notes
-----
The tree data structure consists of nodes with each node consisting of
a number of subclusters. The maximum number of subclusters in a node
is determined by the branching factor. Each subcluster maintains a
linear sum, squared sum and the number of samples in that subcluster.
In addition, each subcluster can also have a node as its child, if the
subcluster is not a member of a leaf node.
For a new point entering the root, it is merged with the subcluster closest
to it and the linear sum, squared sum and the number of samples of that
subcluster are updated. This is done recursively till the properties of
the leaf node are updated.
See :ref:`sphx_glr_auto_examples_cluster_plot_birch_vs_minibatchkmeans.py` for a
comparison with :class:`~sklearn.cluster.MiniBatchKMeans`.
References
----------
* Tian Zhang, Raghu Ramakrishnan, Maron Livny
BIRCH: An efficient data clustering method for large databases.
https://www.cs.sfu.ca/CourseCentral/459/han/papers/zhang96.pdf
* Roberto Perdisci
JBirch - Java implementation of BIRCH clustering algorithm
https://code.google.com/archive/p/jbirch
Examples
--------
>>> from sklearn.cluster import Birch
>>> X = [[0, 1], [0.3, 1], [-0.3, 1], [0, -1], [0.3, -1], [-0.3, -1]]
>>> brc = Birch(n_clusters=None)
>>> brc.fit(X)
Birch(n_clusters=None)
>>> brc.predict(X)
array([0, 0, 0, 1, 1, 1])
For a comparison of the BIRCH clustering algorithm with other clustering algorithms,
see :ref:`sphx_glr_auto_examples_cluster_plot_cluster_comparison.py`
"""
_parameter_constraints: dict = {
"threshold": [Interval(Real, 0.0, None, closed="neither")],
"branching_factor": [Interval(Integral, 1, None, closed="neither")],
"n_clusters": [None, ClusterMixin, Interval(Integral, 1, None, closed="left")],
"compute_labels": ["boolean"],
}
def __init__(
self,
*,
threshold=0.5,
branching_factor=50,
n_clusters=3,
compute_labels=True,
):
self.threshold = threshold
self.branching_factor = branching_factor
self.n_clusters = n_clusters
self.compute_labels = compute_labels
@_fit_context(prefer_skip_nested_validation=True)
def fit(self, X, y=None):
"""
Build a CF Tree for the input data.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
Input data.
y : Ignored
Not used, present here for API consistency by convention.
Returns
-------
self
Fitted estimator.
"""
return self._fit(X, partial=False)
def _fit(self, X, partial):
has_root = getattr(self, "root_", None)
first_call = not (partial and has_root)
X = validate_data(
self,
X,
accept_sparse="csr",
reset=first_call,
dtype=[np.float64, np.float32],
)
threshold = self.threshold
branching_factor = self.branching_factor
n_samples, n_features = X.shape
# If partial_fit is called for the first time or fit is called, we
# start a new tree.
if first_call:
# The first root is the leaf. Manipulate this object throughout.
self.root_ = _CFNode(
threshold=threshold,
branching_factor=branching_factor,
is_leaf=True,
n_features=n_features,
dtype=X.dtype,
)
# To enable getting back subclusters.
self.dummy_leaf_ = _CFNode(
threshold=threshold,
branching_factor=branching_factor,
is_leaf=True,
n_features=n_features,
dtype=X.dtype,
)
self.dummy_leaf_.next_leaf_ = self.root_
self.root_.prev_leaf_ = self.dummy_leaf_
# Cannot vectorize. Enough to convince to use cython.
if not sparse.issparse(X):
iter_func = iter
else:
iter_func = _iterate_sparse_X
for sample in iter_func(X):
subcluster = _CFSubcluster(linear_sum=sample)
split = self.root_.insert_cf_subcluster(subcluster)
if split:
new_subcluster1, new_subcluster2 = _split_node(
self.root_, threshold, branching_factor
)
del self.root_
self.root_ = _CFNode(
threshold=threshold,
branching_factor=branching_factor,
is_leaf=False,
n_features=n_features,
dtype=X.dtype,
)
self.root_.append_subcluster(new_subcluster1)
self.root_.append_subcluster(new_subcluster2)
centroids = np.concatenate([leaf.centroids_ for leaf in self._get_leaves()])
self.subcluster_centers_ = centroids
self._n_features_out = self.subcluster_centers_.shape[0]
self._global_clustering(X)
return self
def _get_leaves(self):
"""
Retrieve the leaves of the CF Node.
Returns
-------
leaves : list of shape (n_leaves,)
List of the leaf nodes.
"""
leaf_ptr = self.dummy_leaf_.next_leaf_
leaves = []
while leaf_ptr is not None:
leaves.append(leaf_ptr)
leaf_ptr = leaf_ptr.next_leaf_
return leaves
@_fit_context(prefer_skip_nested_validation=True)
def partial_fit(self, X=None, y=None):
"""
Online learning. Prevents rebuilding of CFTree from scratch.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features), \
default=None
Input data. If X is not provided, only the global clustering
step is done.
y : Ignored
Not used, present here for API consistency by convention.
Returns
-------
self
Fitted estimator.
"""
if X is None:
# Perform just the final global clustering step.
self._global_clustering()
return self
else:
return self._fit(X, partial=True)
def predict(self, X):
"""
Predict data using the ``centroids_`` of subclusters.
Avoid computation of the row norms of X.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
Input data.
Returns
-------
labels : ndarray of shape(n_samples,)
Labelled data.
"""
check_is_fitted(self)
X = validate_data(self, X, accept_sparse="csr", reset=False)
return self._predict(X)
def _predict(self, X):
"""Predict data using the ``centroids_`` of subclusters."""
kwargs = {"Y_norm_squared": self._subcluster_norms}
with config_context(assume_finite=True):
argmin = pairwise_distances_argmin(
X, self.subcluster_centers_, metric_kwargs=kwargs
)
return self.subcluster_labels_[argmin]
def transform(self, X):
"""
Transform X into subcluster centroids dimension.
Each dimension represents the distance from the sample point to each
cluster centroid.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
Input data.
Returns
-------
X_trans : {array-like, sparse matrix} of shape (n_samples, n_clusters)
Transformed data.
"""
check_is_fitted(self)
X = validate_data(self, X, accept_sparse="csr", reset=False)
with config_context(assume_finite=True):
return euclidean_distances(X, self.subcluster_centers_)
def _global_clustering(self, X=None):
"""
Global clustering for the subclusters obtained after fitting
"""
clusterer = self.n_clusters
centroids = self.subcluster_centers_
compute_labels = (X is not None) and self.compute_labels
# Preprocessing for the global clustering.
not_enough_centroids = False
if isinstance(clusterer, Integral):
clusterer = AgglomerativeClustering(n_clusters=self.n_clusters)
# There is no need to perform the global clustering step.
if len(centroids) < self.n_clusters:
not_enough_centroids = True
# To use in predict to avoid recalculation.
self._subcluster_norms = row_norms(self.subcluster_centers_, squared=True)
if clusterer is None or not_enough_centroids:
self.subcluster_labels_ = np.arange(len(centroids))
if not_enough_centroids:
warnings.warn(
"Number of subclusters found (%d) by BIRCH is less "
"than (%d). Decrease the threshold."
% (len(centroids), self.n_clusters),
ConvergenceWarning,
)
else:
# The global clustering step that clusters the subclusters of
# the leaves. It assumes the centroids of the subclusters as
# samples and finds the final centroids.
self.subcluster_labels_ = clusterer.fit_predict(self.subcluster_centers_)
if compute_labels:
self.labels_ = self._predict(X)
def __sklearn_tags__(self):
tags = super().__sklearn_tags__()
tags.transformer_tags.preserves_dtype = ["float64", "float32"]
tags.input_tags.sparse = True
return tags

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"""Bisecting K-means clustering."""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
import numpy as np
import scipy.sparse as sp
from sklearn.base import _fit_context
from sklearn.cluster._k_means_common import _inertia_dense, _inertia_sparse
from sklearn.cluster._kmeans import (
_BaseKMeans,
_kmeans_single_elkan,
_kmeans_single_lloyd,
_labels_inertia_threadpool_limit,
)
from sklearn.utils._openmp_helpers import _openmp_effective_n_threads
from sklearn.utils._param_validation import Integral, Interval, StrOptions
from sklearn.utils.extmath import row_norms
from sklearn.utils.validation import (
_check_sample_weight,
check_is_fitted,
check_random_state,
validate_data,
)
class _BisectingTree:
"""Tree structure representing the hierarchical clusters of BisectingKMeans."""
def __init__(self, center, indices, score):
"""Create a new cluster node in the tree.
The node holds the center of this cluster and the indices of the data points
that belong to it.
"""
self.center = center
self.indices = indices
self.score = score
self.left = None
self.right = None
def split(self, labels, centers, scores):
"""Split the cluster node into two subclusters."""
self.left = _BisectingTree(
indices=self.indices[labels == 0], center=centers[0], score=scores[0]
)
self.right = _BisectingTree(
indices=self.indices[labels == 1], center=centers[1], score=scores[1]
)
# reset the indices attribute to save memory
self.indices = None
def get_cluster_to_bisect(self):
"""Return the cluster node to bisect next.
It's based on the score of the cluster, which can be either the number of
data points assigned to that cluster or the inertia of that cluster
(see `bisecting_strategy` for details).
"""
max_score = None
for cluster_leaf in self.iter_leaves():
if max_score is None or cluster_leaf.score > max_score:
max_score = cluster_leaf.score
best_cluster_leaf = cluster_leaf
return best_cluster_leaf
def iter_leaves(self):
"""Iterate over all the cluster leaves in the tree."""
if self.left is None:
yield self
else:
yield from self.left.iter_leaves()
yield from self.right.iter_leaves()
class BisectingKMeans(_BaseKMeans):
"""Bisecting K-Means clustering.
Read more in the :ref:`User Guide <bisect_k_means>`.
.. versionadded:: 1.1
Parameters
----------
n_clusters : int, default=8
The number of clusters to form as well as the number of
centroids to generate.
init : {'k-means++', 'random'} or callable, default='random'
Method for initialization:
'k-means++' : selects initial cluster centers for k-mean
clustering in a smart way to speed up convergence. See section
Notes in k_init for more details.
'random': choose `n_clusters` observations (rows) at random from data
for the initial centroids.
If a callable is passed, it should take arguments X, n_clusters and a
random state and return an initialization.
n_init : int, default=1
Number of time the inner k-means algorithm will be run with different
centroid seeds in each bisection.
That will result producing for each bisection best output of n_init
consecutive runs in terms of inertia.
random_state : int, RandomState instance or None, default=None
Determines random number generation for centroid initialization
in inner K-Means. Use an int to make the randomness deterministic.
See :term:`Glossary <random_state>`.
max_iter : int, default=300
Maximum number of iterations of the inner k-means algorithm at each
bisection.
verbose : int, default=0
Verbosity mode.
tol : float, default=1e-4
Relative tolerance with regards to Frobenius norm of the difference
in the cluster centers of two consecutive iterations to declare
convergence. Used in inner k-means algorithm at each bisection to pick
best possible clusters.
copy_x : bool, default=True
When pre-computing distances it is more numerically accurate to center
the data first. If copy_x is True (default), then the original data is
not modified. If False, the original data is modified, and put back
before the function returns, but small numerical differences may be
introduced by subtracting and then adding the data mean. Note that if
the original data is not C-contiguous, a copy will be made even if
copy_x is False. If the original data is sparse, but not in CSR format,
a copy will be made even if copy_x is False.
algorithm : {"lloyd", "elkan"}, default="lloyd"
Inner K-means algorithm used in bisection.
The classical EM-style algorithm is `"lloyd"`.
The `"elkan"` variation can be more efficient on some datasets with
well-defined clusters, by using the triangle inequality. However it's
more memory intensive due to the allocation of an extra array of shape
`(n_samples, n_clusters)`.
bisecting_strategy : {"biggest_inertia", "largest_cluster"},\
default="biggest_inertia"
Defines how bisection should be performed:
- "biggest_inertia" means that BisectingKMeans will always check
all calculated cluster for cluster with biggest SSE
(Sum of squared errors) and bisect it. This approach concentrates on
precision, but may be costly in terms of execution time (especially for
larger amount of data points).
- "largest_cluster" - BisectingKMeans will always split cluster with
largest amount of points assigned to it from all clusters
previously calculated. That should work faster than picking by SSE
('biggest_inertia') and may produce similar results in most cases.
Attributes
----------
cluster_centers_ : ndarray of shape (n_clusters, n_features)
Coordinates of cluster centers. If the algorithm stops before fully
converging (see ``tol`` and ``max_iter``), these will not be
consistent with ``labels_``.
labels_ : ndarray of shape (n_samples,)
Labels of each point.
inertia_ : float
Sum of squared distances of samples to their closest cluster center,
weighted by the sample weights if provided.
n_features_in_ : int
Number of features seen during :term:`fit`.
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
See Also
--------
KMeans : Original implementation of K-Means algorithm.
Notes
-----
It might be inefficient when n_cluster is less than 3, due to unnecessary
calculations for that case.
Examples
--------
>>> from sklearn.cluster import BisectingKMeans
>>> import numpy as np
>>> X = np.array([[1, 1], [10, 1], [3, 1],
... [10, 0], [2, 1], [10, 2],
... [10, 8], [10, 9], [10, 10]])
>>> bisect_means = BisectingKMeans(n_clusters=3, random_state=0).fit(X)
>>> bisect_means.labels_
array([0, 2, 0, 2, 0, 2, 1, 1, 1], dtype=int32)
>>> bisect_means.predict([[0, 0], [12, 3]])
array([0, 2], dtype=int32)
>>> bisect_means.cluster_centers_
array([[ 2., 1.],
[10., 9.],
[10., 1.]])
For a comparison between BisectingKMeans and K-Means refer to example
:ref:`sphx_glr_auto_examples_cluster_plot_bisect_kmeans.py`.
"""
_parameter_constraints: dict = {
**_BaseKMeans._parameter_constraints,
"init": [StrOptions({"k-means++", "random"}), callable],
"n_init": [Interval(Integral, 1, None, closed="left")],
"copy_x": ["boolean"],
"algorithm": [StrOptions({"lloyd", "elkan"})],
"bisecting_strategy": [StrOptions({"biggest_inertia", "largest_cluster"})],
}
def __init__(
self,
n_clusters=8,
*,
init="random",
n_init=1,
random_state=None,
max_iter=300,
verbose=0,
tol=1e-4,
copy_x=True,
algorithm="lloyd",
bisecting_strategy="biggest_inertia",
):
super().__init__(
n_clusters=n_clusters,
init=init,
max_iter=max_iter,
verbose=verbose,
random_state=random_state,
tol=tol,
n_init=n_init,
)
self.copy_x = copy_x
self.algorithm = algorithm
self.bisecting_strategy = bisecting_strategy
def _warn_mkl_vcomp(self, n_active_threads):
"""Warn when vcomp and mkl are both present"""
warnings.warn(
"BisectingKMeans is known to have a memory leak on Windows "
"with MKL, when there are less chunks than available "
"threads. You can avoid it by setting the environment"
f" variable OMP_NUM_THREADS={n_active_threads}."
)
def _inertia_per_cluster(self, X, centers, labels, sample_weight):
"""Calculate the sum of squared errors (inertia) per cluster.
Parameters
----------
X : {ndarray, csr_matrix} of shape (n_samples, n_features)
The input samples.
centers : ndarray of shape (n_clusters=2, n_features)
The cluster centers.
labels : ndarray of shape (n_samples,)
Index of the cluster each sample belongs to.
sample_weight : ndarray of shape (n_samples,)
The weights for each observation in X.
Returns
-------
inertia_per_cluster : ndarray of shape (n_clusters=2,)
Sum of squared errors (inertia) for each cluster.
"""
n_clusters = centers.shape[0] # = 2 since centers comes from a bisection
_inertia = _inertia_sparse if sp.issparse(X) else _inertia_dense
inertia_per_cluster = np.empty(n_clusters)
for label in range(n_clusters):
inertia_per_cluster[label] = _inertia(
X, sample_weight, centers, labels, self._n_threads, single_label=label
)
return inertia_per_cluster
def _bisect(self, X, x_squared_norms, sample_weight, cluster_to_bisect):
"""Split a cluster into 2 subsclusters.
Parameters
----------
X : {ndarray, csr_matrix} of shape (n_samples, n_features)
Training instances to cluster.
x_squared_norms : ndarray of shape (n_samples,)
Squared euclidean norm of each data point.
sample_weight : ndarray of shape (n_samples,)
The weights for each observation in X.
cluster_to_bisect : _BisectingTree node object
The cluster node to split.
"""
X = X[cluster_to_bisect.indices]
x_squared_norms = x_squared_norms[cluster_to_bisect.indices]
sample_weight = sample_weight[cluster_to_bisect.indices]
best_inertia = None
# Split samples in X into 2 clusters.
# Repeating `n_init` times to obtain best clusters
for _ in range(self.n_init):
centers_init = self._init_centroids(
X,
x_squared_norms=x_squared_norms,
init=self.init,
random_state=self._random_state,
n_centroids=2,
sample_weight=sample_weight,
)
labels, inertia, centers, _ = self._kmeans_single(
X,
sample_weight,
centers_init,
max_iter=self.max_iter,
verbose=self.verbose,
tol=self.tol,
n_threads=self._n_threads,
)
# allow small tolerance on the inertia to accommodate for
# non-deterministic rounding errors due to parallel computation
if best_inertia is None or inertia < best_inertia * (1 - 1e-6):
best_labels = labels
best_centers = centers
best_inertia = inertia
if self.verbose:
print(f"New centroids from bisection: {best_centers}")
if self.bisecting_strategy == "biggest_inertia":
scores = self._inertia_per_cluster(
X, best_centers, best_labels, sample_weight
)
else: # bisecting_strategy == "largest_cluster"
# Using minlength to make sure that we have the counts for both labels even
# if all samples are labelled 0.
scores = np.bincount(best_labels, minlength=2)
cluster_to_bisect.split(best_labels, best_centers, scores)
@_fit_context(prefer_skip_nested_validation=True)
def fit(self, X, y=None, sample_weight=None):
"""Compute bisecting k-means clustering.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
Training instances to cluster.
.. note:: The data will be converted to C ordering,
which will cause a memory copy
if the given data is not C-contiguous.
y : Ignored
Not used, present here for API consistency by convention.
sample_weight : array-like of shape (n_samples,), default=None
The weights for each observation in X. If None, all observations
are assigned equal weight. `sample_weight` is not used during
initialization if `init` is a callable.
Returns
-------
self
Fitted estimator.
"""
X = validate_data(
self,
X,
accept_sparse="csr",
dtype=[np.float64, np.float32],
order="C",
copy=self.copy_x,
accept_large_sparse=False,
)
self._check_params_vs_input(X)
self._random_state = check_random_state(self.random_state)
sample_weight = _check_sample_weight(sample_weight, X, dtype=X.dtype)
self._n_threads = _openmp_effective_n_threads()
if self.algorithm == "lloyd" or self.n_clusters == 1:
self._kmeans_single = _kmeans_single_lloyd
self._check_mkl_vcomp(X, X.shape[0])
else:
self._kmeans_single = _kmeans_single_elkan
# Subtract of mean of X for more accurate distance computations
if not sp.issparse(X):
self._X_mean = X.mean(axis=0)
X -= self._X_mean
# Initialize the hierarchical clusters tree
self._bisecting_tree = _BisectingTree(
indices=np.arange(X.shape[0]),
center=X.mean(axis=0),
score=0,
)
x_squared_norms = row_norms(X, squared=True)
for _ in range(self.n_clusters - 1):
# Chose cluster to bisect
cluster_to_bisect = self._bisecting_tree.get_cluster_to_bisect()
# Split this cluster into 2 subclusters
self._bisect(X, x_squared_norms, sample_weight, cluster_to_bisect)
# Aggregate final labels and centers from the bisecting tree
self.labels_ = np.full(X.shape[0], -1, dtype=np.int32)
self.cluster_centers_ = np.empty((self.n_clusters, X.shape[1]), dtype=X.dtype)
for i, cluster_node in enumerate(self._bisecting_tree.iter_leaves()):
self.labels_[cluster_node.indices] = i
self.cluster_centers_[i] = cluster_node.center
cluster_node.label = i # label final clusters for future prediction
cluster_node.indices = None # release memory
# Restore original data
if not sp.issparse(X):
X += self._X_mean
self.cluster_centers_ += self._X_mean
_inertia = _inertia_sparse if sp.issparse(X) else _inertia_dense
self.inertia_ = _inertia(
X, sample_weight, self.cluster_centers_, self.labels_, self._n_threads
)
self._n_features_out = self.cluster_centers_.shape[0]
return self
def predict(self, X):
"""Predict which cluster each sample in X belongs to.
Prediction is made by going down the hierarchical tree
in searching of closest leaf cluster.
In the vector quantization literature, `cluster_centers_` is called
the code book and each value returned by `predict` is the index of
the closest code in the code book.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
New data to predict.
Returns
-------
labels : ndarray of shape (n_samples,)
Index of the cluster each sample belongs to.
"""
check_is_fitted(self)
X = self._check_test_data(X)
x_squared_norms = row_norms(X, squared=True)
# sample weights are unused but necessary in cython helpers
sample_weight = np.ones_like(x_squared_norms)
labels = self._predict_recursive(X, sample_weight, self._bisecting_tree)
return labels
def _predict_recursive(self, X, sample_weight, cluster_node):
"""Predict recursively by going down the hierarchical tree.
Parameters
----------
X : {ndarray, csr_matrix} of shape (n_samples, n_features)
The data points, currently assigned to `cluster_node`, to predict between
the subclusters of this node.
sample_weight : ndarray of shape (n_samples,)
The weights for each observation in X.
cluster_node : _BisectingTree node object
The cluster node of the hierarchical tree.
Returns
-------
labels : ndarray of shape (n_samples,)
Index of the cluster each sample belongs to.
"""
if cluster_node.left is None:
# This cluster has no subcluster. Labels are just the label of the cluster.
return np.full(X.shape[0], cluster_node.label, dtype=np.int32)
# Determine if data points belong to the left or right subcluster
centers = np.vstack((cluster_node.left.center, cluster_node.right.center))
if hasattr(self, "_X_mean"):
centers += self._X_mean
cluster_labels = _labels_inertia_threadpool_limit(
X,
sample_weight,
centers,
self._n_threads,
return_inertia=False,
)
mask = cluster_labels == 0
# Compute the labels for each subset of the data points.
labels = np.full(X.shape[0], -1, dtype=np.int32)
labels[mask] = self._predict_recursive(
X[mask], sample_weight[mask], cluster_node.left
)
labels[~mask] = self._predict_recursive(
X[~mask], sample_weight[~mask], cluster_node.right
)
return labels
def __sklearn_tags__(self):
tags = super().__sklearn_tags__()
tags.input_tags.sparse = True
tags.transformer_tags.preserves_dtype = ["float64", "float32"]
return tags

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@@ -0,0 +1,512 @@
"""
DBSCAN: Density-Based Spatial Clustering of Applications with Noise
"""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
from numbers import Integral, Real
import numpy as np
from scipy import sparse
from sklearn.base import BaseEstimator, ClusterMixin, _fit_context
from sklearn.cluster._dbscan_inner import dbscan_inner
from sklearn.metrics.pairwise import _VALID_METRICS
from sklearn.neighbors import NearestNeighbors
from sklearn.utils._param_validation import Interval, StrOptions, validate_params
from sklearn.utils.validation import _check_sample_weight, validate_data
@validate_params(
{
"X": ["array-like", "sparse matrix"],
"sample_weight": ["array-like", None],
},
prefer_skip_nested_validation=False,
)
def dbscan(
X,
eps=0.5,
*,
min_samples=5,
metric="minkowski",
metric_params=None,
algorithm="auto",
leaf_size=30,
p=2,
sample_weight=None,
n_jobs=None,
):
"""Perform DBSCAN clustering from vector array or distance matrix.
This function is a wrapper around :class:`~cluster.DBSCAN`, suitable for
quick, standalone clustering tasks. For estimator-based workflows, where
estimator attributes or pipeline integration is required, prefer
:class:`~cluster.DBSCAN`.
DBSCAN (Density-Based Spatial Clustering of Applications with Noise) is a
density-based clustering algorithm that groups together points that are
closely packed while marking points in low-density regions as outliers.
Read more in the :ref:`User Guide <dbscan>`.
Parameters
----------
X : {array-like, scipy sparse matrix} of shape (n_samples, n_features) or \
(n_samples, n_samples)
A feature array, or array of distances between samples if
``metric='precomputed'``. When using precomputed distances, X must
be a square symmetric matrix.
eps : float, default=0.5
The maximum distance between two samples for one to be considered
as in the neighborhood of the other. This is not a maximum bound
on the distances of points within a cluster. This is the most
important DBSCAN parameter to choose appropriately for your data set
and distance function. Smaller values result in more clusters,
while larger values result in fewer, larger clusters.
min_samples : int, default=5
The number of samples (or total weight) in a neighborhood for a point
to be considered as a core point. This includes the point itself.
Higher values yield fewer, denser clusters, while lower values yield
more, sparser clusters.
metric : str or callable, default='minkowski'
The metric to use when calculating distance between instances in a
feature array. If metric is a string or callable, it must be one of
the options allowed by :func:`sklearn.metrics.pairwise_distances` for
its metric parameter.
If metric is "precomputed", X is assumed to be a distance matrix and
must be square during fit.
X may be a :term:`sparse graph <sparse graph>`,
in which case only "nonzero" elements may be considered neighbors.
metric_params : dict, default=None
Additional keyword arguments for the metric function.
.. versionadded:: 0.19
algorithm : {'auto', 'ball_tree', 'kd_tree', 'brute'}, default='auto'
The algorithm to be used by the NearestNeighbors module
to compute pointwise distances and find nearest neighbors.
'auto' will attempt to decide the most appropriate algorithm
based on the values passed to :meth:`fit` method.
See :class:`~sklearn.neighbors.NearestNeighbors` documentation for
details.
leaf_size : int, default=30
Leaf size passed to BallTree or cKDTree. This can affect the speed
of the construction and query, as well as the memory required
to store the tree. The optimal value depends
on the nature of the problem. Generally, smaller leaf sizes
lead to faster queries but slower construction.
p : float, default=2
Power parameter for the Minkowski metric. When p = 1, this is equivalent
to using manhattan_distance (l1), and euclidean_distance (l2) for p = 2.
For arbitrary p, minkowski_distance (l_p) is used. This parameter is expected
to be positive.
sample_weight : array-like of shape (n_samples,), default=None
Weight of each sample, such that a sample with a weight of at least
``min_samples`` is by itself a core sample; a sample with negative
weight may inhibit its eps-neighbor from being core.
Note that weights are absolute, and default to 1.
n_jobs : int, default=None
The number of parallel jobs to run for neighbors search. ``None`` means
1 unless in a :obj:`joblib.parallel_backend` context. ``-1`` means
using all processors. See :term:`Glossary <n_jobs>` for more details.
If precomputed distances are used, parallel execution is not available
and thus n_jobs will have no effect.
Returns
-------
core_samples : ndarray of shape (n_core_samples,)
Indices of core samples.
labels : ndarray of shape (n_samples,)
Cluster labels for each point. Noisy samples are given the label -1.
Non-negative integers indicate cluster membership.
See Also
--------
DBSCAN : An estimator interface for this clustering algorithm.
OPTICS : A similar estimator interface clustering at multiple values of
eps. Our implementation is optimized for memory usage.
Notes
-----
For an example, see :ref:`sphx_glr_auto_examples_cluster_plot_dbscan.py`.
This implementation bulk-computes all neighborhood queries, which increases
the memory complexity to O(n.d) where d is the average number of neighbors,
while original DBSCAN had memory complexity O(n). It may attract a higher
memory complexity when querying these nearest neighborhoods, depending
on the ``algorithm``.
One way to avoid the query complexity is to pre-compute sparse
neighborhoods in chunks using
:func:`NearestNeighbors.radius_neighbors_graph
<sklearn.neighbors.NearestNeighbors.radius_neighbors_graph>` with
``mode='distance'``, then using ``metric='precomputed'`` here.
Another way to reduce memory and computation time is to remove
(near-)duplicate points and use ``sample_weight`` instead.
:class:`~sklearn.cluster.OPTICS` provides a similar clustering with lower
memory usage.
References
----------
Ester, M., H. P. Kriegel, J. Sander, and X. Xu, `"A Density-Based
Algorithm for Discovering Clusters in Large Spatial Databases with Noise"
<https://www.dbs.ifi.lmu.de/Publikationen/Papers/KDD-96.final.frame.pdf>`_.
In: Proceedings of the 2nd International Conference on Knowledge Discovery
and Data Mining, Portland, OR, AAAI Press, pp. 226-231. 1996
Schubert, E., Sander, J., Ester, M., Kriegel, H. P., & Xu, X. (2017).
:doi:`"DBSCAN revisited, revisited: why and how you should (still) use DBSCAN."
<10.1145/3068335>`
ACM Transactions on Database Systems (TODS), 42(3), 19.
Examples
--------
>>> from sklearn.cluster import dbscan
>>> X = [[1, 2], [2, 2], [2, 3], [8, 7], [8, 8], [25, 80]]
>>> core_samples, labels = dbscan(X, eps=3, min_samples=2)
>>> core_samples
array([0, 1, 2, 3, 4])
>>> labels
array([ 0, 0, 0, 1, 1, -1])
"""
est = DBSCAN(
eps=eps,
min_samples=min_samples,
metric=metric,
metric_params=metric_params,
algorithm=algorithm,
leaf_size=leaf_size,
p=p,
n_jobs=n_jobs,
)
est.fit(X, sample_weight=sample_weight)
return est.core_sample_indices_, est.labels_
class DBSCAN(ClusterMixin, BaseEstimator):
"""Perform DBSCAN clustering from vector array or distance matrix.
DBSCAN - Density-Based Spatial Clustering of Applications with Noise.
Finds core samples of high density and expands clusters from them.
This algorithm is particularly good for data which contains clusters of
similar density and can find clusters of arbitrary shape.
Unlike K-means, DBSCAN does not require specifying the number of clusters
in advance and can identify outliers as noise points.
This implementation has a worst case memory complexity of :math:`O({n}^2)`,
which can occur when the `eps` param is large and `min_samples` is low,
while the original DBSCAN only uses linear memory.
For further details, see the Notes below.
Read more in the :ref:`User Guide <dbscan>`.
Parameters
----------
eps : float, default=0.5
The maximum distance between two samples for one to be considered
as in the neighborhood of the other. This is not a maximum bound
on the distances of points within a cluster. This is the most
important DBSCAN parameter to choose appropriately for your data set
and distance function. Smaller values generally lead to more clusters.
min_samples : int, default=5
The number of samples (or total weight) in a neighborhood for a point to
be considered as a core point. This includes the point itself. If
`min_samples` is set to a higher value, DBSCAN will find denser clusters,
whereas if it is set to a lower value, the found clusters will be more
sparse.
metric : str, or callable, default='euclidean'
The metric to use when calculating distance between instances in a
feature array. If metric is a string or callable, it must be one of
the options allowed by :func:`sklearn.metrics.pairwise_distances` for
its metric parameter.
If metric is "precomputed", X is assumed to be a distance matrix and
must be square. X may be a :term:`sparse graph`, in which
case only "nonzero" elements may be considered neighbors for DBSCAN.
.. versionadded:: 0.17
metric *precomputed* to accept precomputed sparse matrix.
metric_params : dict, default=None
Additional keyword arguments for the metric function.
.. versionadded:: 0.19
algorithm : {'auto', 'ball_tree', 'kd_tree', 'brute'}, default='auto'
The algorithm to be used by the NearestNeighbors module
to compute pointwise distances and find nearest neighbors.
'auto' will attempt to decide the most appropriate algorithm
based on the values passed to :meth:`fit` method.
See :class:`~sklearn.neighbors.NearestNeighbors` documentation for
details.
leaf_size : int, default=30
Leaf size passed to BallTree or cKDTree. This can affect the speed
of the construction and query, as well as the memory required
to store the tree. The optimal value depends
on the nature of the problem.
p : float, default=None
The power of the Minkowski metric to be used to calculate distance
between points. If None, then ``p=2`` (equivalent to the Euclidean
distance). When p=1, this is equivalent to Manhattan distance.
n_jobs : int, default=None
The number of parallel jobs to run.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
Attributes
----------
core_sample_indices_ : ndarray of shape (n_core_samples,)
Indices of core samples.
components_ : ndarray of shape (n_core_samples, n_features)
Copy of each core sample found by training.
labels_ : ndarray of shape (n_samples,)
Cluster labels for each point in the dataset given to fit().
Noisy samples are given the label -1. Non-negative integers
indicate cluster membership.
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
OPTICS : A similar clustering at multiple values of eps. Our implementation
is optimized for memory usage.
Notes
-----
This implementation bulk-computes all neighborhood queries, which increases
the memory complexity to O(n.d) where d is the average number of neighbors,
while original DBSCAN had memory complexity O(n). It may attract a higher
memory complexity when querying these nearest neighborhoods, depending
on the ``algorithm``.
One way to avoid the query complexity is to pre-compute sparse
neighborhoods in chunks using
:func:`NearestNeighbors.radius_neighbors_graph
<sklearn.neighbors.NearestNeighbors.radius_neighbors_graph>` with
``mode='distance'``, then using ``metric='precomputed'`` here.
Another way to reduce memory and computation time is to remove
(near-)duplicate points and use ``sample_weight`` instead.
:class:`~sklearn.cluster.OPTICS` provides a similar clustering with lower memory
usage.
References
----------
Ester, M., H. P. Kriegel, J. Sander, and X. Xu, `"A Density-Based
Algorithm for Discovering Clusters in Large Spatial Databases with Noise"
<https://www.dbs.ifi.lmu.de/Publikationen/Papers/KDD-96.final.frame.pdf>`_.
In: Proceedings of the 2nd International Conference on Knowledge Discovery
and Data Mining, Portland, OR, AAAI Press, pp. 226-231. 1996
Schubert, E., Sander, J., Ester, M., Kriegel, H. P., & Xu, X. (2017).
:doi:`"DBSCAN revisited, revisited: why and how you should (still) use DBSCAN."
<10.1145/3068335>`
ACM Transactions on Database Systems (TODS), 42(3), 19.
Examples
--------
>>> from sklearn.cluster import DBSCAN
>>> import numpy as np
>>> X = np.array([[1, 2], [2, 2], [2, 3],
... [8, 7], [8, 8], [25, 80]])
>>> clustering = DBSCAN(eps=3, min_samples=2).fit(X)
>>> clustering.labels_
array([ 0, 0, 0, 1, 1, -1])
>>> clustering
DBSCAN(eps=3, min_samples=2)
For an example, see
:ref:`sphx_glr_auto_examples_cluster_plot_dbscan.py`.
For a comparison of DBSCAN with other clustering algorithms, see
:ref:`sphx_glr_auto_examples_cluster_plot_cluster_comparison.py`
"""
_parameter_constraints: dict = {
"eps": [Interval(Real, 0.0, None, closed="neither")],
"min_samples": [Interval(Integral, 1, None, closed="left")],
"metric": [
StrOptions(set(_VALID_METRICS) | {"precomputed"}),
callable,
],
"metric_params": [dict, None],
"algorithm": [StrOptions({"auto", "ball_tree", "kd_tree", "brute"})],
"leaf_size": [Interval(Integral, 1, None, closed="left")],
"p": [Interval(Real, 0.0, None, closed="left"), None],
"n_jobs": [Integral, None],
}
def __init__(
self,
eps=0.5,
*,
min_samples=5,
metric="euclidean",
metric_params=None,
algorithm="auto",
leaf_size=30,
p=None,
n_jobs=None,
):
self.eps = eps
self.min_samples = min_samples
self.metric = metric
self.metric_params = metric_params
self.algorithm = algorithm
self.leaf_size = leaf_size
self.p = p
self.n_jobs = n_jobs
@_fit_context(
# DBSCAN.metric is not validated yet
prefer_skip_nested_validation=False
)
def fit(self, X, y=None, sample_weight=None):
"""Perform DBSCAN clustering from features, or distance matrix.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features), or \
(n_samples, n_samples)
Training instances to cluster, or distances between instances if
``metric='precomputed'``. If a sparse matrix is provided, it will
be converted into a sparse ``csr_matrix``.
y : Ignored
Not used, present here for API consistency by convention.
sample_weight : array-like of shape (n_samples,), default=None
Weight of each sample, such that a sample with a weight of at least
``min_samples`` is by itself a core sample; a sample with a
negative weight may inhibit its eps-neighbor from being core.
Note that weights are absolute, and default to 1.
Returns
-------
self : object
Returns a fitted instance of self.
"""
X = validate_data(self, X, accept_sparse="csr")
if sample_weight is not None:
sample_weight = _check_sample_weight(sample_weight, X)
# Calculate neighborhood for all samples. This leaves the original
# point in, which needs to be considered later (i.e. point i is in the
# neighborhood of point i. While True, its useless information)
if self.metric == "precomputed" and sparse.issparse(X):
# set the diagonal to explicit values, as a point is its own
# neighbor
X = X.copy() # copy to avoid in-place modification
with warnings.catch_warnings():
warnings.simplefilter("ignore", sparse.SparseEfficiencyWarning)
X.setdiag(X.diagonal())
neighbors_model = NearestNeighbors(
radius=self.eps,
algorithm=self.algorithm,
leaf_size=self.leaf_size,
metric=self.metric,
metric_params=self.metric_params,
p=self.p,
n_jobs=self.n_jobs,
)
neighbors_model.fit(X)
# This has worst case O(n^2) memory complexity
neighborhoods = neighbors_model.radius_neighbors(X, return_distance=False)
if sample_weight is None:
n_neighbors = np.array([len(neighbors) for neighbors in neighborhoods])
else:
n_neighbors = np.array(
[np.sum(sample_weight[neighbors]) for neighbors in neighborhoods]
)
# Initially, all samples are noise.
labels = np.full(X.shape[0], -1, dtype=np.intp)
# A list of all core samples found.
core_samples = np.asarray(n_neighbors >= self.min_samples, dtype=np.uint8)
dbscan_inner(core_samples, neighborhoods, labels)
self.core_sample_indices_ = np.where(core_samples)[0]
self.labels_ = labels
if len(self.core_sample_indices_):
# fix for scipy sparse indexing issue
self.components_ = X[self.core_sample_indices_].copy()
else:
# no core samples
self.components_ = np.empty((0, X.shape[1]))
return self
def fit_predict(self, X, y=None, sample_weight=None):
"""Compute clusters from a data or distance matrix and predict labels.
This method fits the model and returns the cluster labels in a single step.
It is equivalent to calling fit(X).labels_.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features), or \
(n_samples, n_samples)
Training instances to cluster, or distances between instances if
``metric='precomputed'``. If a sparse matrix is provided, it will
be converted into a sparse ``csr_matrix``.
y : Ignored
Not used, present here for API consistency by convention.
sample_weight : array-like of shape (n_samples,), default=None
Weight of each sample, such that a sample with a weight of at least
``min_samples`` is by itself a core sample; a sample with a
negative weight may inhibit its eps-neighbor from being core.
Note that weights are absolute, and default to 1.
Returns
-------
labels : ndarray of shape (n_samples,)
Cluster labels. Noisy samples are given the label -1.
Non-negative integers indicate cluster membership.
"""
self.fit(X, sample_weight=sample_weight)
return self.labels_
def __sklearn_tags__(self):
tags = super().__sklearn_tags__()
tags.input_tags.pairwise = self.metric == "precomputed"
tags.input_tags.sparse = True
return tags

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@@ -0,0 +1,41 @@
# Fast inner loop for DBSCAN.
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
from libcpp.vector cimport vector
from sklearn.utils._typedefs cimport uint8_t, intp_t
def dbscan_inner(const uint8_t[::1] is_core,
object[:] neighborhoods,
intp_t[::1] labels):
cdef intp_t i, label_num = 0, v
cdef intp_t[:] neighb
cdef vector[intp_t] stack
for i in range(labels.shape[0]):
if labels[i] != -1 or not is_core[i]:
continue
# Depth-first search starting from i, ending at the non-core points.
# This is very similar to the classic algorithm for computing connected
# components, the difference being that we label non-core points as
# part of a cluster (component), but don't expand their neighborhoods.
while True:
if labels[i] == -1:
labels[i] = label_num
if is_core[i]:
neighb = neighborhoods[i]
for i in range(neighb.shape[0]):
v = neighb[i]
if labels[v] == -1:
stack.push_back(v)
if stack.size() == 0:
break
i = stack.back()
stack.pop_back()
label_num += 1

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@@ -0,0 +1,76 @@
"""
Feature agglomeration. Base classes and functions for performing feature
agglomeration.
"""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import numpy as np
from scipy.sparse import issparse
from sklearn.base import TransformerMixin
from sklearn.utils.validation import check_is_fitted, validate_data
###############################################################################
# Mixin class for feature agglomeration.
class AgglomerationTransform(TransformerMixin):
"""
A class for feature agglomeration via the transform interface.
"""
def transform(self, X):
"""
Transform a new matrix using the built clustering.
Parameters
----------
X : array-like of shape (n_samples, n_features) or \
(n_samples, n_samples)
An M by N array of M observations in N dimensions or a length
M array of M one-dimensional observations.
Returns
-------
Y : ndarray of shape (n_samples, n_clusters) or (n_clusters,)
The pooled values for each feature cluster.
"""
check_is_fitted(self)
X = validate_data(self, X, reset=False)
if self.pooling_func == np.mean and not issparse(X):
size = np.bincount(self.labels_)
n_samples = X.shape[0]
# a fast way to compute the mean of grouped features
nX = np.array(
[np.bincount(self.labels_, X[i, :]) / size for i in range(n_samples)]
)
else:
nX = [
self.pooling_func(X[:, self.labels_ == l], axis=1)
for l in np.unique(self.labels_)
]
nX = np.array(nX).T
return nX
def inverse_transform(self, X):
"""
Inverse the transformation and return a vector of size `n_features`.
Parameters
----------
X : array-like of shape (n_samples, n_clusters) or (n_clusters,)
The values to be assigned to each cluster of samples.
Returns
-------
X_original : ndarray of shape (n_samples, n_features) or (n_features,)
A vector of size `n_samples` with the values of `X` assigned to
each of the cluster of samples.
"""
check_is_fitted(self)
unil, inverse = np.unique(self.labels_, return_inverse=True)
return X[..., inverse]

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# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause

View File

@@ -0,0 +1,274 @@
# Minimum spanning tree single linkage implementation for hdbscan
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
cimport numpy as cnp
from libc.float cimport DBL_MAX
import numpy as np
from sklearn.metrics._dist_metrics cimport DistanceMetric64
from sklearn.cluster._hierarchical_fast cimport UnionFind
from sklearn.cluster._hdbscan._tree cimport HIERARCHY_t
from sklearn.cluster._hdbscan._tree import HIERARCHY_dtype
from sklearn.utils._typedefs cimport intp_t, float64_t, int64_t, uint8_t
cnp.import_array()
cdef extern from "numpy/arrayobject.h":
intp_t * PyArray_SHAPE(cnp.PyArrayObject *)
# Numpy structured dtype representing a single ordered edge in Prim's algorithm
MST_edge_dtype = np.dtype([
("current_node", np.int64),
("next_node", np.int64),
("distance", np.float64),
])
# Packed shouldn't make a difference since they're all 8-byte quantities,
# but it's included just to be safe.
ctypedef packed struct MST_edge_t:
int64_t current_node
int64_t next_node
float64_t distance
cpdef cnp.ndarray[MST_edge_t, ndim=1, mode='c'] mst_from_mutual_reachability(
cnp.ndarray[float64_t, ndim=2] mutual_reachability
):
"""Compute the Minimum Spanning Tree (MST) representation of the mutual-
reachability graph using Prim's algorithm.
Parameters
----------
mutual_reachability : ndarray of shape (n_samples, n_samples)
Array of mutual-reachabilities between samples.
Returns
-------
mst : ndarray of shape (n_samples - 1,), dtype=MST_edge_dtype
The MST representation of the mutual-reachability graph. The MST is
represented as a collection of edges.
"""
cdef:
# Note: we utilize ndarray's over memory-views to make use of numpy
# binary indexing and sub-selection below.
cnp.ndarray[int64_t, ndim=1, mode='c'] current_labels
cnp.ndarray[float64_t, ndim=1, mode='c'] min_reachability, left, right
cnp.ndarray[MST_edge_t, ndim=1, mode='c'] mst
cnp.ndarray[uint8_t, mode='c'] label_filter
int64_t n_samples = PyArray_SHAPE(<cnp.PyArrayObject*> mutual_reachability)[0]
int64_t current_node, new_node_index, new_node, i
mst = np.empty(n_samples - 1, dtype=MST_edge_dtype)
current_labels = np.arange(n_samples, dtype=np.int64)
current_node = 0
min_reachability = np.full(n_samples, fill_value=np.inf, dtype=np.float64)
for i in range(0, n_samples - 1):
label_filter = current_labels != current_node
current_labels = current_labels[label_filter]
left = min_reachability[label_filter]
right = mutual_reachability[current_node][current_labels]
min_reachability = np.minimum(left, right)
new_node_index = np.argmin(min_reachability)
new_node = current_labels[new_node_index]
mst[i].current_node = current_node
mst[i].next_node = new_node
mst[i].distance = min_reachability[new_node_index]
current_node = new_node
return mst
cpdef cnp.ndarray[MST_edge_t, ndim=1, mode='c'] mst_from_data_matrix(
const float64_t[:, ::1] raw_data,
const float64_t[::1] core_distances,
DistanceMetric64 dist_metric,
float64_t alpha=1.0
):
"""Compute the Minimum Spanning Tree (MST) representation of the mutual-
reachability graph generated from the provided `raw_data` and
`core_distances` using Prim's algorithm.
Parameters
----------
raw_data : ndarray of shape (n_samples, n_features)
Input array of data samples.
core_distances : ndarray of shape (n_samples,)
An array containing the core-distance calculated for each corresponding
sample.
dist_metric : DistanceMetric
The distance metric to use when calculating pairwise distances for
determining mutual-reachability.
Returns
-------
mst : ndarray of shape (n_samples - 1,), dtype=MST_edge_dtype
The MST representation of the mutual-reachability graph. The MST is
represented as a collection of edges.
"""
cdef:
uint8_t[::1] in_tree
float64_t[::1] min_reachability
int64_t[::1] current_sources
cnp.ndarray[MST_edge_t, ndim=1, mode='c'] mst
int64_t current_node, source_node, new_node, next_node_source
int64_t i, j, n_samples, num_features
float64_t current_node_core_dist, new_reachability, mutual_reachability_distance
float64_t next_node_min_reach, pair_distance, next_node_core_dist
n_samples = raw_data.shape[0]
num_features = raw_data.shape[1]
mst = np.empty(n_samples - 1, dtype=MST_edge_dtype)
in_tree = np.zeros(n_samples, dtype=np.uint8)
min_reachability = np.full(n_samples, fill_value=np.inf, dtype=np.float64)
current_sources = np.ones(n_samples, dtype=np.int64)
current_node = 0
# The following loop dynamically updates minimum reachability node-by-node,
# avoiding unnecessary computation where possible.
for i in range(0, n_samples - 1):
in_tree[current_node] = 1
current_node_core_dist = core_distances[current_node]
new_reachability = DBL_MAX
source_node = 0
new_node = 0
for j in range(n_samples):
if in_tree[j]:
continue
next_node_min_reach = min_reachability[j]
next_node_source = current_sources[j]
pair_distance = dist_metric.dist(
&raw_data[current_node, 0],
&raw_data[j, 0],
num_features
)
pair_distance /= alpha
next_node_core_dist = core_distances[j]
mutual_reachability_distance = max(
current_node_core_dist,
next_node_core_dist,
pair_distance
)
# If MRD(i, j) is smaller than node j's min_reachability, we update
# node j's min_reachability for future reference.
if mutual_reachability_distance < next_node_min_reach:
min_reachability[j] = mutual_reachability_distance
current_sources[j] = current_node
# If MRD(i, j) is also smaller than node i's current
# min_reachability, we update and set their edge as the current
# MST edge candidate.
if mutual_reachability_distance < new_reachability:
new_reachability = mutual_reachability_distance
source_node = current_node
new_node = j
# If the node j is closer to another node already in the tree, we
# make their edge the current MST candidate edge.
elif next_node_min_reach < new_reachability:
new_reachability = next_node_min_reach
source_node = next_node_source
new_node = j
mst[i].current_node = source_node
mst[i].next_node = new_node
mst[i].distance = new_reachability
current_node = new_node
return mst
cpdef cnp.ndarray[HIERARCHY_t, ndim=1, mode="c"] make_single_linkage(const MST_edge_t[::1] mst):
"""Construct a single-linkage tree from an MST.
Parameters
----------
mst : ndarray of shape (n_samples - 1,), dtype=MST_edge_dtype
The MST representation of the mutual-reachability graph. The MST is
represented as a collection of edges.
Returns
-------
single_linkage : ndarray of shape (n_samples - 1,), dtype=HIERARCHY_dtype
The single-linkage tree tree (dendrogram) built from the MST. Each
of the array represents the following:
- left node/cluster
- right node/cluster
- distance
- new cluster size
"""
cdef:
cnp.ndarray[HIERARCHY_t, ndim=1, mode="c"] single_linkage
# Note mst.shape[0] is one fewer than the number of samples
int64_t n_samples = mst.shape[0] + 1
intp_t current_node_cluster, next_node_cluster
int64_t current_node, next_node, i
float64_t distance
UnionFind U = UnionFind(n_samples)
single_linkage = np.zeros(n_samples - 1, dtype=HIERARCHY_dtype)
for i in range(n_samples - 1):
current_node = mst[i].current_node
next_node = mst[i].next_node
distance = mst[i].distance
current_node_cluster = U.fast_find(current_node)
next_node_cluster = U.fast_find(next_node)
single_linkage[i].left_node = current_node_cluster
single_linkage[i].right_node = next_node_cluster
single_linkage[i].value = distance
single_linkage[i].cluster_size = U.size[current_node_cluster] + U.size[next_node_cluster]
U.union(current_node_cluster, next_node_cluster)
return single_linkage

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# mutual reachability distance computations
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
cimport numpy as cnp
import numpy as np
from scipy.sparse import issparse
from cython cimport floating, integral
from libc.math cimport isfinite, INFINITY
from sklearn.utils._typedefs cimport intp_t
cnp.import_array()
def mutual_reachability_graph(
distance_matrix, min_samples=5, max_distance=0.0
):
"""Compute the weighted adjacency matrix of the mutual reachability graph.
The mutual reachability distance used to build the graph is defined as::
max(d_core(x_p), d_core(x_q), d(x_p, x_q))
and the core distance `d_core` is defined as the distance between a point
`x_p` and its k-th nearest neighbor.
Note that all computations are done in-place.
Parameters
----------
distance_matrix : {ndarray, sparse matrix} of shape (n_samples, n_samples)
Array of distances between samples. If sparse, the array must be in
`CSR` format.
min_samples : int, default=5
The parameter `k` used to calculate the distance between a point
`x_p` and its k-th nearest neighbor.
max_distance : float, default=0.0
The distance which `np.inf` is replaced with. When the true mutual-
reachability distance is measured to be infinite, it is instead
truncated to `max_dist`. Only used when `distance_matrix` is a sparse
matrix.
Returns
-------
mututal_reachability_graph: {ndarray, sparse matrix} of shape \
(n_samples, n_samples)
Weighted adjacency matrix of the mutual reachability graph.
References
----------
.. [1] Campello, R. J., Moulavi, D., & Sander, J. (2013, April).
Density-based clustering based on hierarchical density estimates.
In Pacific-Asia Conference on Knowledge Discovery and Data Mining
(pp. 160-172). Springer Berlin Heidelberg.
"""
further_neighbor_idx = min_samples - 1
if issparse(distance_matrix):
if distance_matrix.format != "csr":
raise ValueError(
"Only sparse CSR matrices are supported for `distance_matrix`."
)
_sparse_mutual_reachability_graph(
distance_matrix.data,
distance_matrix.indices,
distance_matrix.indptr,
distance_matrix.shape[0],
further_neighbor_idx=further_neighbor_idx,
max_distance=max_distance,
)
else:
_dense_mutual_reachability_graph(
distance_matrix, further_neighbor_idx=further_neighbor_idx
)
return distance_matrix
def _dense_mutual_reachability_graph(
floating[:, :] distance_matrix,
intp_t further_neighbor_idx,
):
"""Dense implementation of mutual reachability graph.
The computation is done in-place, i.e. the distance matrix is modified
directly.
Parameters
----------
distance_matrix : ndarray of shape (n_samples, n_samples)
Array of distances between samples.
further_neighbor_idx : int
The index of the furthest neighbor to use to define the core distances.
"""
cdef:
intp_t i, j, n_samples = distance_matrix.shape[0]
floating mutual_reachability_distance
floating[::1] core_distances
# We assume that the distance matrix is symmetric. We choose to sort every
# row to have the same implementation than the sparse case that requires
# CSR matrix.
core_distances = np.ascontiguousarray(
np.partition(
distance_matrix, further_neighbor_idx, axis=1
)[:, further_neighbor_idx]
)
with nogil:
# TODO: Update w/ prange with thread count based on
# _openmp_effective_n_threads
for i in range(n_samples):
for j in range(n_samples):
mutual_reachability_distance = max(
core_distances[i],
core_distances[j],
distance_matrix[i, j],
)
distance_matrix[i, j] = mutual_reachability_distance
def _sparse_mutual_reachability_graph(
cnp.ndarray[floating, ndim=1, mode="c"] data,
cnp.ndarray[integral, ndim=1, mode="c"] indices,
cnp.ndarray[integral, ndim=1, mode="c"] indptr,
intp_t n_samples,
intp_t further_neighbor_idx,
floating max_distance,
):
"""Sparse implementation of mutual reachability graph.
The computation is done in-place, i.e. the distance matrix is modified
directly. This implementation only accepts `CSR` format sparse matrices.
Parameters
----------
distance_matrix : sparse matrix of shape (n_samples, n_samples)
Sparse matrix of distances between samples. The sparse format should
be `CSR`.
further_neighbor_idx : int
The index of the furthest neighbor to use to define the core distances.
max_distance : float
The distance which `np.inf` is replaced with. When the true mutual-
reachability distance is measured to be infinite, it is instead
truncated to `max_dist`. Only used when `distance_matrix` is a sparse
matrix.
"""
cdef:
integral i, col_ind, row_ind
floating mutual_reachability_distance
floating[:] core_distances
floating[:] row_data
if floating is float:
dtype = np.float32
else:
dtype = np.float64
core_distances = np.empty(n_samples, dtype=dtype)
for i in range(n_samples):
row_data = data[indptr[i]:indptr[i + 1]]
if further_neighbor_idx < row_data.size:
core_distances[i] = np.partition(
row_data, further_neighbor_idx
)[further_neighbor_idx]
else:
core_distances[i] = INFINITY
with nogil:
for row_ind in range(n_samples):
for i in range(indptr[row_ind], indptr[row_ind + 1]):
col_ind = indices[i]
mutual_reachability_distance = max(
core_distances[row_ind], core_distances[col_ind], data[i]
)
if isfinite(mutual_reachability_distance):
data[i] = mutual_reachability_distance
elif max_distance > 0:
data[i] = max_distance

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# Copyright (c) 2015, Leland McInnes
# All rights reserved.
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
from sklearn.utils._typedefs cimport intp_t, float64_t, uint8_t
cimport numpy as cnp
# This corresponds to the scipy.cluster.hierarchy format
ctypedef packed struct HIERARCHY_t:
intp_t left_node
intp_t right_node
float64_t value
intp_t cluster_size
# Effectively an edgelist encoding a parent/child pair, along with a value and
# the corresponding cluster_size in each row providing a tree structure.
ctypedef packed struct CONDENSED_t:
intp_t parent
intp_t child
float64_t value
intp_t cluster_size
cdef extern from "numpy/arrayobject.h":
intp_t * PyArray_SHAPE(cnp.PyArrayObject *)

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@@ -0,0 +1,799 @@
# Tree handling (condensing, finding stable clusters) for hdbscan
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
cimport numpy as cnp
from libc.math cimport isinf
import cython
import numpy as np
cnp.import_array()
cdef extern from "numpy/arrayobject.h":
intp_t * PyArray_SHAPE(cnp.PyArrayObject *)
cdef cnp.float64_t INFTY = np.inf
cdef cnp.intp_t NOISE = -1
HIERARCHY_dtype = np.dtype([
("left_node", np.intp),
("right_node", np.intp),
("value", np.float64),
("cluster_size", np.intp),
])
CONDENSED_dtype = np.dtype([
("parent", np.intp),
("child", np.intp),
("value", np.float64),
("cluster_size", np.intp),
])
cpdef tuple tree_to_labels(
const HIERARCHY_t[::1] single_linkage_tree,
cnp.intp_t min_cluster_size=10,
cluster_selection_method="eom",
bint allow_single_cluster=False,
cnp.float64_t cluster_selection_epsilon=0.0,
max_cluster_size=None,
):
cdef:
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree
cnp.ndarray[cnp.intp_t, ndim=1, mode='c'] labels
cnp.ndarray[cnp.float64_t, ndim=1, mode='c'] probabilities
condensed_tree = _condense_tree(single_linkage_tree, min_cluster_size)
labels, probabilities = _get_clusters(
condensed_tree,
_compute_stability(condensed_tree),
cluster_selection_method,
allow_single_cluster,
cluster_selection_epsilon,
max_cluster_size,
)
return (labels, probabilities)
cdef list bfs_from_hierarchy(
const HIERARCHY_t[::1] hierarchy,
cnp.intp_t bfs_root
):
"""
Perform a breadth first search on a tree in scipy hclust format.
"""
cdef list process_queue, next_queue, result
cdef cnp.intp_t n_samples = hierarchy.shape[0] + 1
cdef cnp.intp_t node
process_queue = [bfs_root]
result = []
while process_queue:
result.extend(process_queue)
# By construction, node i is formed by the union of nodes
# hierarchy[i - n_samples, 0] and hierarchy[i - n_samples, 1]
process_queue = [
x - n_samples
for x in process_queue
if x >= n_samples
]
if process_queue:
next_queue = []
for node in process_queue:
next_queue.extend(
[
hierarchy[node].left_node,
hierarchy[node].right_node,
]
)
process_queue = next_queue
return result
cpdef cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] _condense_tree(
const HIERARCHY_t[::1] hierarchy,
cnp.intp_t min_cluster_size=10
):
"""Condense a tree according to a minimum cluster size. This is akin
to the runt pruning procedure of Stuetzle. The result is a much simpler
tree that is easier to visualize. We include extra information on the
lambda value at which individual points depart clusters for later
analysis and computation.
Parameters
----------
hierarchy : ndarray of shape (n_samples,), dtype=HIERARCHY_dtype
A single linkage hierarchy in scipy.cluster.hierarchy format.
min_cluster_size : int, optional (default 10)
The minimum size of clusters to consider. Clusters smaller than this
are pruned from the tree.
Returns
-------
condensed_tree : ndarray of shape (n_samples,), dtype=CONDENSED_dtype
Effectively an edgelist encoding a parent/child pair, along with a
value and the corresponding cluster_size in each row providing a tree
structure.
"""
cdef:
cnp.intp_t root = 2 * hierarchy.shape[0]
cnp.intp_t n_samples = hierarchy.shape[0] + 1
cnp.intp_t next_label = n_samples + 1
list result_list, node_list = bfs_from_hierarchy(hierarchy, root)
cnp.intp_t[::1] relabel
cnp.uint8_t[::1] ignore
cnp.intp_t node, sub_node, left, right
cnp.float64_t lambda_value, distance
cnp.intp_t left_count, right_count
HIERARCHY_t children
relabel = np.empty(root + 1, dtype=np.intp)
relabel[root] = n_samples
result_list = []
ignore = np.zeros(len(node_list), dtype=bool)
for node in node_list:
if ignore[node] or node < n_samples:
continue
children = hierarchy[node - n_samples]
left = children.left_node
right = children.right_node
distance = children.value
if distance > 0.0:
lambda_value = 1.0 / distance
else:
lambda_value = INFTY
if left >= n_samples:
left_count = hierarchy[left - n_samples].cluster_size
else:
left_count = 1
if right >= n_samples:
right_count = hierarchy[right - n_samples].cluster_size
else:
right_count = 1
if left_count >= min_cluster_size and right_count >= min_cluster_size:
relabel[left] = next_label
next_label += 1
result_list.append(
(relabel[node], relabel[left], lambda_value, left_count)
)
relabel[right] = next_label
next_label += 1
result_list.append(
(relabel[node], relabel[right], lambda_value, right_count)
)
elif left_count < min_cluster_size and right_count < min_cluster_size:
for sub_node in bfs_from_hierarchy(hierarchy, left):
if sub_node < n_samples:
result_list.append(
(relabel[node], sub_node, lambda_value, 1)
)
ignore[sub_node] = True
for sub_node in bfs_from_hierarchy(hierarchy, right):
if sub_node < n_samples:
result_list.append(
(relabel[node], sub_node, lambda_value, 1)
)
ignore[sub_node] = True
elif left_count < min_cluster_size:
relabel[right] = relabel[node]
for sub_node in bfs_from_hierarchy(hierarchy, left):
if sub_node < n_samples:
result_list.append(
(relabel[node], sub_node, lambda_value, 1)
)
ignore[sub_node] = True
else:
relabel[left] = relabel[node]
for sub_node in bfs_from_hierarchy(hierarchy, right):
if sub_node < n_samples:
result_list.append(
(relabel[node], sub_node, lambda_value, 1)
)
ignore[sub_node] = True
return np.array(result_list, dtype=CONDENSED_dtype)
cdef dict _compute_stability(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree
):
cdef:
cnp.float64_t[::1] result, births
cnp.intp_t[:] parents = condensed_tree['parent']
cnp.intp_t parent, cluster_size, result_index, idx
cnp.float64_t lambda_val
CONDENSED_t condensed_node
cnp.intp_t largest_child = condensed_tree['child'].max()
cnp.intp_t smallest_cluster = np.min(parents)
cnp.intp_t num_clusters = np.max(parents) - smallest_cluster + 1
dict stability_dict = {}
largest_child = max(largest_child, smallest_cluster)
births = np.full(largest_child + 1, np.nan, dtype=np.float64)
for idx in range(PyArray_SHAPE(<cnp.PyArrayObject*> condensed_tree)[0]):
condensed_node = condensed_tree[idx]
births[condensed_node.child] = condensed_node.value
births[smallest_cluster] = 0.0
result = np.zeros(num_clusters, dtype=np.float64)
for idx in range(PyArray_SHAPE(<cnp.PyArrayObject*> condensed_tree)[0]):
condensed_node = condensed_tree[idx]
parent = condensed_node.parent
lambda_val = condensed_node.value
cluster_size = condensed_node.cluster_size
result_index = parent - smallest_cluster
result[result_index] += (lambda_val - births[parent]) * cluster_size
for idx in range(num_clusters):
stability_dict[idx + smallest_cluster] = result[idx]
return stability_dict
cdef list bfs_from_cluster_tree(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree,
cnp.intp_t bfs_root
):
cdef:
list result = []
cnp.ndarray[cnp.intp_t, ndim=1] process_queue = (
np.array([bfs_root], dtype=np.intp)
)
cnp.ndarray[cnp.intp_t, ndim=1] children = condensed_tree['child']
cnp.intp_t[:] parents = condensed_tree['parent']
while len(process_queue) > 0:
result.extend(process_queue.tolist())
process_queue = children[np.isin(parents, process_queue)]
return result
cdef cnp.float64_t[::1] max_lambdas(cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree):
cdef:
cnp.intp_t parent, current_parent, idx
cnp.float64_t lambda_val, max_lambda
cnp.float64_t[::1] deaths
cnp.intp_t largest_parent = condensed_tree['parent'].max()
deaths = np.zeros(largest_parent + 1, dtype=np.float64)
current_parent = condensed_tree[0].parent
max_lambda = condensed_tree[0].value
for idx in range(1, PyArray_SHAPE(<cnp.PyArrayObject*> condensed_tree)[0]):
parent = condensed_tree[idx].parent
lambda_val = condensed_tree[idx].value
if parent == current_parent:
max_lambda = max(max_lambda, lambda_val)
else:
deaths[current_parent] = max_lambda
current_parent = parent
max_lambda = lambda_val
deaths[current_parent] = max_lambda # value for last parent
return deaths
@cython.final
cdef class TreeUnionFind:
cdef cnp.intp_t[:, ::1] data
cdef cnp.uint8_t[::1] is_component
def __init__(self, size):
cdef cnp.intp_t idx
self.data = np.zeros((size, 2), dtype=np.intp)
for idx in range(size):
self.data[idx, 0] = idx
self.is_component = np.ones(size, dtype=np.uint8)
cdef void union(self, cnp.intp_t x, cnp.intp_t y):
cdef cnp.intp_t x_root = self.find(x)
cdef cnp.intp_t y_root = self.find(y)
if self.data[x_root, 1] < self.data[y_root, 1]:
self.data[x_root, 0] = y_root
elif self.data[x_root, 1] > self.data[y_root, 1]:
self.data[y_root, 0] = x_root
else:
self.data[y_root, 0] = x_root
self.data[x_root, 1] += 1
return
cdef cnp.intp_t find(self, cnp.intp_t x):
if self.data[x, 0] != x:
self.data[x, 0] = self.find(self.data[x, 0])
self.is_component[x] = False
return self.data[x, 0]
cpdef cnp.ndarray[cnp.intp_t, ndim=1, mode='c'] labelling_at_cut(
const HIERARCHY_t[::1] linkage,
cnp.float64_t cut,
cnp.intp_t min_cluster_size
):
"""Given a single linkage tree and a cut value, return the
vector of cluster labels at that cut value. This is useful
for Robust Single Linkage, and extracting DBSCAN results
from a single HDBSCAN run.
Parameters
----------
linkage : ndarray of shape (n_samples,), dtype=HIERARCHY_dtype
The single linkage tree in scipy.cluster.hierarchy format.
cut : double
The cut value at which to find clusters.
min_cluster_size : int
The minimum cluster size; clusters below this size at
the cut will be considered noise.
Returns
-------
labels : ndarray of shape (n_samples,)
The cluster labels for each point in the data set;
a label of -1 denotes a noise assignment.
"""
cdef:
cnp.intp_t n, cluster, root, n_samples, cluster_label
cnp.intp_t[::1] unique_labels, cluster_size
cnp.ndarray[cnp.intp_t, ndim=1, mode='c'] result
TreeUnionFind union_find
dict cluster_label_map
HIERARCHY_t node
root = 2 * linkage.shape[0]
n_samples = root // 2 + 1
result = np.empty(n_samples, dtype=np.intp)
union_find = TreeUnionFind(root + 1)
cluster = n_samples
for node in linkage:
if node.value < cut:
union_find.union(node.left_node, cluster)
union_find.union(node.right_node, cluster)
cluster += 1
cluster_size = np.zeros(cluster, dtype=np.intp)
for n in range(n_samples):
cluster = union_find.find(n)
cluster_size[cluster] += 1
result[n] = cluster
cluster_label_map = {-1: NOISE}
cluster_label = 0
unique_labels = np.unique(result)
for cluster in unique_labels:
if cluster_size[cluster] < min_cluster_size:
cluster_label_map[cluster] = NOISE
else:
cluster_label_map[cluster] = cluster_label
cluster_label += 1
for n in range(n_samples):
result[n] = cluster_label_map[result[n]]
return result
cpdef cnp.ndarray[cnp.intp_t, ndim=1, mode='c'] _do_labelling(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree,
set clusters,
dict cluster_label_map,
cnp.intp_t allow_single_cluster,
cnp.float64_t cluster_selection_epsilon
):
"""Given a condensed tree, clusters and a labeling map for the clusters,
return an array containing the labels of each point based on cluster
membership. Note that this is where points may be marked as noisy
outliers. The determination of some points as noise is in large, single-
cluster datasets is controlled by the `allow_single_cluster` and
`cluster_selection_epsilon` parameters.
Parameters
----------
condensed_tree : ndarray of shape (n_samples,), dtype=CONDENSED_dtype
Effectively an edgelist encoding a parent/child pair, along with a
value and the corresponding cluster_size in each row providing a tree
structure.
clusters : set
The set of nodes corresponding to identified clusters. These node
values should be the same as those present in `condensed_tree`.
cluster_label_map : dict
A mapping from the node values present in `clusters` to the labels
which will be returned.
Returns
-------
labels : ndarray of shape (n_samples,)
The cluster labels for each point in the data set;
a label of -1 denotes a noise assignment.
"""
cdef:
cnp.intp_t root_cluster
cnp.ndarray[cnp.intp_t, ndim=1, mode='c'] result
cnp.ndarray[cnp.intp_t, ndim=1] parent_array, child_array
cnp.ndarray[cnp.float64_t, ndim=1] lambda_array
TreeUnionFind union_find
cnp.intp_t n, parent, child, cluster
cnp.float64_t threshold
child_array = condensed_tree['child']
parent_array = condensed_tree['parent']
lambda_array = condensed_tree['value']
root_cluster = np.min(parent_array)
result = np.empty(root_cluster, dtype=np.intp)
union_find = TreeUnionFind(np.max(parent_array) + 1)
for n in range(PyArray_SHAPE(<cnp.PyArrayObject*> condensed_tree)[0]):
child = child_array[n]
parent = parent_array[n]
if child not in clusters:
union_find.union(parent, child)
for n in range(root_cluster):
cluster = union_find.find(n)
label = NOISE
if cluster != root_cluster:
label = cluster_label_map[cluster]
elif len(clusters) == 1 and allow_single_cluster:
# There can only be one edge with this particular child hence this
# expression extracts a unique, scalar lambda value.
parent_lambda = lambda_array[child_array == n]
if cluster_selection_epsilon != 0.0:
threshold = 1 / cluster_selection_epsilon
else:
# The threshold should be calculated per-sample based on the
# largest lambda of any simbling node.
threshold = lambda_array[parent_array == cluster].max()
if parent_lambda >= threshold:
label = cluster_label_map[cluster]
result[n] = label
return result
cdef cnp.ndarray[cnp.float64_t, ndim=1, mode='c'] get_probabilities(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree,
dict cluster_map,
cnp.intp_t[::1] labels
):
cdef:
cnp.ndarray[cnp.float64_t, ndim=1, mode='c'] result
cnp.float64_t[:] lambda_array
cnp.float64_t[::1] deaths
cnp.intp_t[:] child_array, parent_array
cnp.intp_t root_cluster, n, point, cluster_num, cluster
cnp.float64_t max_lambda, lambda_val
child_array = condensed_tree['child']
parent_array = condensed_tree['parent']
lambda_array = condensed_tree['value']
result = np.zeros(labels.shape[0])
deaths = max_lambdas(condensed_tree)
root_cluster = np.min(parent_array)
for n in range(PyArray_SHAPE(<cnp.PyArrayObject*> condensed_tree)[0]):
point = child_array[n]
if point >= root_cluster:
continue
cluster_num = labels[point]
if cluster_num == -1:
continue
cluster = cluster_map[cluster_num]
max_lambda = deaths[cluster]
if max_lambda == 0.0 or isinf(lambda_array[n]):
result[point] = 1.0
else:
lambda_val = min(lambda_array[n], max_lambda)
result[point] = lambda_val / max_lambda
return result
cpdef list recurse_leaf_dfs(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] cluster_tree,
cnp.intp_t current_node
):
cdef cnp.intp_t[:] children
cdef cnp.intp_t child
children = cluster_tree[cluster_tree['parent'] == current_node]['child']
if children.shape[0] == 0:
return [current_node,]
else:
return sum([recurse_leaf_dfs(cluster_tree, child) for child in children], [])
cpdef list get_cluster_tree_leaves(cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] cluster_tree):
cdef cnp.intp_t root
if PyArray_SHAPE(<cnp.PyArrayObject*> cluster_tree)[0] == 0:
return []
root = cluster_tree['parent'].min()
return recurse_leaf_dfs(cluster_tree, root)
cdef cnp.intp_t traverse_upwards(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] cluster_tree,
cnp.float64_t cluster_selection_epsilon,
cnp.intp_t leaf,
cnp.intp_t allow_single_cluster
):
cdef cnp.intp_t root, parent
cdef cnp.float64_t parent_eps
root = cluster_tree['parent'].min()
parent = cluster_tree[cluster_tree['child'] == leaf]['parent']
if parent == root:
if allow_single_cluster:
return parent
else:
return leaf # return node closest to root
parent_eps = 1 / cluster_tree[cluster_tree['child'] == parent]['value']
if parent_eps > cluster_selection_epsilon:
return parent
else:
return traverse_upwards(
cluster_tree,
cluster_selection_epsilon,
parent,
allow_single_cluster
)
cdef set epsilon_search(
set leaves,
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] cluster_tree,
cnp.float64_t cluster_selection_epsilon,
cnp.intp_t allow_single_cluster
):
cdef:
list selected_clusters = list()
list processed = list()
cnp.intp_t leaf, epsilon_child, sub_node
cnp.float64_t eps
cnp.uint8_t[:] leaf_nodes
cnp.ndarray[cnp.intp_t, ndim=1] children = cluster_tree['child']
cnp.ndarray[cnp.float64_t, ndim=1] distances = cluster_tree['value']
for leaf in leaves:
leaf_nodes = children == leaf
eps = 1 / distances[leaf_nodes][0]
if eps < cluster_selection_epsilon:
if leaf not in processed:
epsilon_child = traverse_upwards(
cluster_tree,
cluster_selection_epsilon,
leaf,
allow_single_cluster
)
selected_clusters.append(epsilon_child)
for sub_node in bfs_from_cluster_tree(cluster_tree, epsilon_child):
if sub_node != epsilon_child:
processed.append(sub_node)
else:
selected_clusters.append(leaf)
return set(selected_clusters)
@cython.wraparound(True)
cdef tuple _get_clusters(
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] condensed_tree,
dict stability,
cluster_selection_method='eom',
cnp.uint8_t allow_single_cluster=False,
cnp.float64_t cluster_selection_epsilon=0.0,
max_cluster_size=None
):
"""Given a tree and stability dict, produce the cluster labels
(and probabilities) for a flat clustering based on the chosen
cluster selection method.
Parameters
----------
condensed_tree : ndarray of shape (n_samples,), dtype=CONDENSED_dtype
Effectively an edgelist encoding a parent/child pair, along with a
value and the corresponding cluster_size in each row providing a tree
structure.
stability : dict
A dictionary mapping cluster_ids to stability values
cluster_selection_method : string, optional (default 'eom')
The method of selecting clusters. The default is the
Excess of Mass algorithm specified by 'eom'. The alternate
option is 'leaf'.
allow_single_cluster : boolean, optional (default False)
Whether to allow a single cluster to be selected by the
Excess of Mass algorithm.
cluster_selection_epsilon: double, optional (default 0.0)
A distance threshold for cluster splits.
max_cluster_size: int, default=None
The maximum size for clusters located by the EOM clusterer. Can
be overridden by the cluster_selection_epsilon parameter in
rare cases.
Returns
-------
labels : ndarray of shape (n_samples,)
An integer array of cluster labels, with -1 denoting noise.
probabilities : ndarray (n_samples,)
The cluster membership strength of each sample.
stabilities : ndarray (n_clusters,)
The cluster coherence strengths of each cluster.
"""
cdef:
list node_list
cnp.ndarray[CONDENSED_t, ndim=1, mode='c'] cluster_tree
cnp.uint8_t[::1] child_selection
cnp.ndarray[cnp.intp_t, ndim=1, mode='c'] labels
dict is_cluster, cluster_sizes
cnp.float64_t subtree_stability
cnp.intp_t node, sub_node, cluster, n_samples
cnp.ndarray[cnp.float64_t, ndim=1, mode='c'] probs
# Assume clusters are ordered by numeric id equivalent to
# a topological sort of the tree; This is valid given the
# current implementation above, so don't change that ... or
# if you do, change this accordingly!
if allow_single_cluster:
node_list = sorted(stability.keys(), reverse=True)
else:
node_list = sorted(stability.keys(), reverse=True)[:-1]
# (exclude root)
cluster_tree = condensed_tree[condensed_tree['cluster_size'] > 1]
is_cluster = {cluster: True for cluster in node_list}
n_samples = np.max(condensed_tree[condensed_tree['cluster_size'] == 1]['child']) + 1
if max_cluster_size is None:
max_cluster_size = n_samples + 1 # Set to a value that will never be triggered
cluster_sizes = {
child: cluster_size for child, cluster_size
in zip(cluster_tree['child'], cluster_tree['cluster_size'])
}
if allow_single_cluster:
# Compute cluster size for the root node
cluster_sizes[node_list[-1]] = np.sum(
cluster_tree[cluster_tree['parent'] == node_list[-1]]['cluster_size'])
if cluster_selection_method == 'eom':
for node in node_list:
child_selection = (cluster_tree['parent'] == node)
subtree_stability = np.sum([
stability[child] for
child in cluster_tree['child'][child_selection]])
if subtree_stability > stability[node] or cluster_sizes[node] > max_cluster_size:
is_cluster[node] = False
stability[node] = subtree_stability
else:
for sub_node in bfs_from_cluster_tree(cluster_tree, node):
if sub_node != node:
is_cluster[sub_node] = False
if cluster_selection_epsilon != 0.0 and PyArray_SHAPE(<cnp.PyArrayObject*> cluster_tree)[0] > 0:
eom_clusters = [c for c in is_cluster if is_cluster[c]]
selected_clusters = []
# first check if eom_clusters only has root node, which skips epsilon check.
if (len(eom_clusters) == 1 and eom_clusters[0] == cluster_tree['parent'].min()):
if allow_single_cluster:
selected_clusters = eom_clusters
else:
selected_clusters = epsilon_search(
set(eom_clusters),
cluster_tree,
cluster_selection_epsilon,
allow_single_cluster
)
for c in is_cluster:
if c in selected_clusters:
is_cluster[c] = True
else:
is_cluster[c] = False
elif cluster_selection_method == 'leaf':
leaves = set(get_cluster_tree_leaves(cluster_tree))
if len(leaves) == 0:
for c in is_cluster:
is_cluster[c] = False
is_cluster[condensed_tree['parent'].min()] = True
if cluster_selection_epsilon != 0.0:
selected_clusters = epsilon_search(
leaves,
cluster_tree,
cluster_selection_epsilon,
allow_single_cluster
)
else:
selected_clusters = leaves
for c in is_cluster:
if c in selected_clusters:
is_cluster[c] = True
else:
is_cluster[c] = False
clusters = {c for c in is_cluster if is_cluster[c]}
cluster_map = {c: n for n, c in enumerate(sorted(list(clusters)))}
reverse_cluster_map = {n: c for c, n in cluster_map.items()}
labels = _do_labelling(
condensed_tree,
clusters,
cluster_map,
allow_single_cluster,
cluster_selection_epsilon
)
probs = get_probabilities(condensed_tree, reverse_cluster_map, labels)
return (labels, probs)

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@@ -0,0 +1,15 @@
cluster_hdbscan_extension_metadata = {
'_linkage': {'sources': [cython_gen.process('_linkage.pyx'), metrics_cython_tree]},
'_reachability': {'sources': [cython_gen.process('_reachability.pyx')]},
'_tree': {'sources': [cython_gen.process('_tree.pyx')]}
}
foreach ext_name, ext_dict : cluster_hdbscan_extension_metadata
py.extension_module(
ext_name,
ext_dict.get('sources'),
dependencies: [np_dep],
subdir: 'sklearn/cluster/_hdbscan',
install: true
)
endforeach

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@@ -0,0 +1,63 @@
import numpy as np
import pytest
from sklearn.cluster._hdbscan._reachability import mutual_reachability_graph
from sklearn.utils._testing import (
_convert_container,
assert_allclose,
)
def test_mutual_reachability_graph_error_sparse_format():
"""Check that we raise an error if the sparse format is not CSR."""
rng = np.random.RandomState(0)
X = rng.randn(10, 10)
X = X.T @ X
np.fill_diagonal(X, 0.0)
X = _convert_container(X, "sparse_csc")
err_msg = "Only sparse CSR matrices are supported"
with pytest.raises(ValueError, match=err_msg):
mutual_reachability_graph(X)
@pytest.mark.parametrize("array_type", ["array", "sparse_csr"])
def test_mutual_reachability_graph_inplace(array_type):
"""Check that the operation is happening inplace."""
rng = np.random.RandomState(0)
X = rng.randn(10, 10)
X = X.T @ X
np.fill_diagonal(X, 0.0)
X = _convert_container(X, array_type)
mr_graph = mutual_reachability_graph(X)
assert id(mr_graph) == id(X)
def test_mutual_reachability_graph_equivalence_dense_sparse():
"""Check that we get the same results for dense and sparse implementation."""
rng = np.random.RandomState(0)
X = rng.randn(5, 5)
X_dense = X.T @ X
X_sparse = _convert_container(X_dense, "sparse_csr")
mr_graph_dense = mutual_reachability_graph(X_dense, min_samples=3)
mr_graph_sparse = mutual_reachability_graph(X_sparse, min_samples=3)
assert_allclose(mr_graph_dense, mr_graph_sparse.toarray())
@pytest.mark.parametrize("array_type", ["array", "sparse_csr"])
@pytest.mark.parametrize("dtype", [np.float32, np.float64])
def test_mutual_reachability_graph_preserves_dtype(array_type, dtype):
"""Check that the computation preserve dtype thanks to fused types."""
rng = np.random.RandomState(0)
X = rng.randn(10, 10)
X = (X.T @ X).astype(dtype)
np.fill_diagonal(X, 0.0)
X = _convert_container(X, array_type)
assert X.dtype == dtype
mr_graph = mutual_reachability_graph(X)
assert mr_graph.dtype == dtype

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@@ -0,0 +1,9 @@
from sklearn.utils._typedefs cimport intp_t
cdef class UnionFind:
cdef intp_t next_label
cdef intp_t[:] parent
cdef intp_t[:] size
cdef void union(self, intp_t m, intp_t n) noexcept
cdef intp_t fast_find(self, intp_t n) noexcept

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@@ -0,0 +1,507 @@
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import numpy as np
cimport cython
from sklearn.metrics._dist_metrics cimport DistanceMetric64
from sklearn.utils._fast_dict cimport IntFloatDict
from sklearn.utils._typedefs cimport float64_t, intp_t, uint8_t
# C++
from cython.operator cimport dereference as deref, preincrement as inc
from libcpp.map cimport map as cpp_map
from libc.math cimport fmax, INFINITY
###############################################################################
# Utilities for computing the ward momentum
def compute_ward_dist(
const float64_t[::1] m_1,
const float64_t[:, ::1] m_2,
const intp_t[::1] coord_row,
const intp_t[::1] coord_col,
float64_t[::1] res
):
cdef intp_t size_max = coord_row.shape[0]
cdef intp_t n_features = m_2.shape[1]
cdef intp_t i, j, row, col
cdef float64_t pa, n
for i in range(size_max):
row = coord_row[i]
col = coord_col[i]
n = (m_1[row] * m_1[col]) / (m_1[row] + m_1[col])
pa = 0.
for j in range(n_features):
pa += (m_2[row, j] / m_1[row] - m_2[col, j] / m_1[col]) ** 2
res[i] = pa * n
###############################################################################
# Utilities for cutting and exploring a hierarchical tree
def _hc_get_descendent(intp_t node, children, intp_t n_leaves):
"""
Function returning all the descendent leaves of a set of nodes in the tree.
Parameters
----------
node : integer
The node for which we want the descendents.
children : list of pairs, length n_nodes
The children of each non-leaf node. Values less than `n_samples` refer
to leaves of the tree. A greater value `i` indicates a node with
children `children[i - n_samples]`.
n_leaves : integer
Number of leaves.
Returns
-------
descendent : list of int
"""
ind = [node]
if node < n_leaves:
return ind
descendent = []
# It is actually faster to do the accounting of the number of
# elements is the list ourselves: len is a lengthy operation on a
# chained list
cdef intp_t i, n_indices = 1
while n_indices:
i = ind.pop()
if i < n_leaves:
descendent.append(i)
n_indices -= 1
else:
ind.extend(children[i - n_leaves])
n_indices += 1
return descendent
def hc_get_heads(intp_t[:] parents, copy=True):
"""Returns the heads of the forest, as defined by parents.
Parameters
----------
parents : array of integers
The parent structure defining the forest (ensemble of trees)
copy : boolean
If copy is False, the input 'parents' array is modified inplace
Returns
-------
heads : array of integers of same shape as parents
The indices in the 'parents' of the tree heads
"""
cdef intp_t parent, node0, node, size
if copy:
parents = np.copy(parents)
size = parents.size
# Start from the top of the tree and go down
for node0 in range(size - 1, -1, -1):
node = node0
parent = parents[node]
while parent != node:
parents[node0] = parent
node = parent
parent = parents[node]
return parents
def _get_parents(
nodes,
heads,
const intp_t[:] parents,
uint8_t[::1] not_visited
):
"""Returns the heads of the given nodes, as defined by parents.
Modifies 'heads' and 'not_visited' in-place.
Parameters
----------
nodes : list of integers
The nodes to start from
heads : list of integers
A list to hold the results (modified inplace)
parents : array of integers
The parent structure defining the tree
not_visited
The tree nodes to consider (modified inplace)
"""
cdef intp_t parent, node
for node in nodes:
parent = parents[node]
while parent != node:
node = parent
parent = parents[node]
if not_visited[node]:
not_visited[node] = 0
heads.append(node)
###############################################################################
# merge strategies implemented on IntFloatDicts
# These are used in the hierarchical clustering code, to implement
# merging between two clusters, defined as a dict containing node number
# as keys and edge weights as values.
def max_merge(
IntFloatDict a,
IntFloatDict b,
const intp_t[:] mask,
intp_t n_a,
intp_t n_b
):
"""Merge two IntFloatDicts with the max strategy: when the same key is
present in the two dicts, the max of the two values is used.
Parameters
==========
a, b : IntFloatDict object
The IntFloatDicts to merge
mask : ndarray array of dtype integer and of dimension 1
a mask for keys to ignore: if not mask[key] the corresponding key
is skipped in the output dictionary
n_a, n_b : float
n_a and n_b are weights for a and b for the merge strategy.
They are not used in the case of a max merge.
Returns
=======
out : IntFloatDict object
The IntFloatDict resulting from the merge
"""
cdef IntFloatDict out_obj = IntFloatDict.__new__(IntFloatDict)
cdef cpp_map[intp_t, float64_t].iterator a_it = a.my_map.begin()
cdef cpp_map[intp_t, float64_t].iterator a_end = a.my_map.end()
cdef intp_t key
cdef float64_t value
# First copy a into out
while a_it != a_end:
key = deref(a_it).first
if mask[key]:
out_obj.my_map[key] = deref(a_it).second
inc(a_it)
# Then merge b into out
cdef cpp_map[intp_t, float64_t].iterator out_it = out_obj.my_map.begin()
cdef cpp_map[intp_t, float64_t].iterator out_end = out_obj.my_map.end()
cdef cpp_map[intp_t, float64_t].iterator b_it = b.my_map.begin()
cdef cpp_map[intp_t, float64_t].iterator b_end = b.my_map.end()
while b_it != b_end:
key = deref(b_it).first
value = deref(b_it).second
if mask[key]:
out_it = out_obj.my_map.find(key)
if out_it == out_end:
# Key not found
out_obj.my_map[key] = value
else:
deref(out_it).second = fmax(deref(out_it).second, value)
inc(b_it)
return out_obj
def average_merge(
IntFloatDict a,
IntFloatDict b,
const intp_t[:] mask,
intp_t n_a,
intp_t n_b
):
"""Merge two IntFloatDicts with the average strategy: when the
same key is present in the two dicts, the weighted average of the two
values is used.
Parameters
==========
a, b : IntFloatDict object
The IntFloatDicts to merge
mask : ndarray array of dtype integer and of dimension 1
a mask for keys to ignore: if not mask[key] the corresponding key
is skipped in the output dictionary
n_a, n_b : float
n_a and n_b are weights for a and b for the merge strategy.
They are used for a weighted mean.
Returns
=======
out : IntFloatDict object
The IntFloatDict resulting from the merge
"""
cdef IntFloatDict out_obj = IntFloatDict.__new__(IntFloatDict)
cdef cpp_map[intp_t, float64_t].iterator a_it = a.my_map.begin()
cdef cpp_map[intp_t, float64_t].iterator a_end = a.my_map.end()
cdef intp_t key
cdef float64_t value
cdef float64_t n_out = <float64_t> (n_a + n_b)
# First copy a into out
while a_it != a_end:
key = deref(a_it).first
if mask[key]:
out_obj.my_map[key] = deref(a_it).second
inc(a_it)
# Then merge b into out
cdef cpp_map[intp_t, float64_t].iterator out_it = out_obj.my_map.begin()
cdef cpp_map[intp_t, float64_t].iterator out_end = out_obj.my_map.end()
cdef cpp_map[intp_t, float64_t].iterator b_it = b.my_map.begin()
cdef cpp_map[intp_t, float64_t].iterator b_end = b.my_map.end()
while b_it != b_end:
key = deref(b_it).first
value = deref(b_it).second
if mask[key]:
out_it = out_obj.my_map.find(key)
if out_it == out_end:
# Key not found
out_obj.my_map[key] = value
else:
deref(out_it).second = (n_a * deref(out_it).second
+ n_b * value) / n_out
inc(b_it)
return out_obj
###############################################################################
# An edge object for fast comparisons
cdef class WeightedEdge:
cdef public intp_t a
cdef public intp_t b
cdef public float64_t weight
def __init__(self, float64_t weight, intp_t a, intp_t b):
self.weight = weight
self.a = a
self.b = b
def __richcmp__(self, WeightedEdge other, int op):
"""Cython-specific comparison method.
op is the comparison code::
< 0
== 2
> 4
<= 1
!= 3
>= 5
"""
if op == 0:
return self.weight < other.weight
elif op == 1:
return self.weight <= other.weight
elif op == 2:
return self.weight == other.weight
elif op == 3:
return self.weight != other.weight
elif op == 4:
return self.weight > other.weight
elif op == 5:
return self.weight >= other.weight
def __repr__(self):
return "%s(weight=%f, a=%i, b=%i)" % (self.__class__.__name__,
self.weight,
self.a, self.b)
################################################################################
# Efficient labelling/conversion of MSTs to single linkage hierarchies
cdef class UnionFind(object):
def __init__(self, N):
self.parent = np.full(2 * N - 1, -1., dtype=np.intp, order='C')
self.next_label = N
self.size = np.hstack((np.ones(N, dtype=np.intp),
np.zeros(N - 1, dtype=np.intp)))
cdef void union(self, intp_t m, intp_t n) noexcept:
self.parent[m] = self.next_label
self.parent[n] = self.next_label
self.size[self.next_label] = self.size[m] + self.size[n]
self.next_label += 1
return
@cython.wraparound(True)
cdef intp_t fast_find(self, intp_t n) noexcept:
cdef intp_t p
p = n
# find the highest node in the linkage graph so far
while self.parent[n] != -1:
n = self.parent[n]
# provide a shortcut up to the highest node
while self.parent[p] != n:
p, self.parent[p] = self.parent[p], n
return n
def _single_linkage_label(const float64_t[:, :] L):
"""
Convert a linkage array or MST to a tree by labelling clusters at merges.
This is done by using a Union find structure to keep track of merges
efficiently. This is the private version of the function that assumes that
``L`` has been properly validated. See ``single_linkage_label`` for the
user facing version of this function.
Parameters
----------
L: array of shape (n_samples - 1, 3)
The linkage array or MST where each row specifies two samples
to be merged and a distance or weight at which the merge occurs. This
array is assumed to be sorted by the distance/weight.
Returns
-------
A tree in the format used by scipy.cluster.hierarchy.
"""
cdef float64_t[:, ::1] result_arr
cdef intp_t left, left_cluster, right, right_cluster, index
cdef float64_t delta
result_arr = np.zeros((L.shape[0], 4), dtype=np.float64)
U = UnionFind(L.shape[0] + 1)
for index in range(L.shape[0]):
left = <intp_t> L[index, 0]
right = <intp_t> L[index, 1]
delta = L[index, 2]
left_cluster = U.fast_find(left)
right_cluster = U.fast_find(right)
result_arr[index][0] = left_cluster
result_arr[index][1] = right_cluster
result_arr[index][2] = delta
result_arr[index][3] = U.size[left_cluster] + U.size[right_cluster]
U.union(left_cluster, right_cluster)
return np.asarray(result_arr)
@cython.wraparound(True)
def single_linkage_label(L):
"""
Convert a linkage array or MST to a tree by labelling clusters at merges.
This is done by using a Union find structure to keep track of merges
efficiently.
Parameters
----------
L: array of shape (n_samples - 1, 3)
The linkage array or MST where each row specifies two samples
to be merged and a distance or weight at which the merge occurs. This
array is assumed to be sorted by the distance/weight.
Returns
-------
A tree in the format used by scipy.cluster.hierarchy.
"""
# Validate L
if L[:, :2].min() < 0 or L[:, :2].max() >= 2 * L.shape[0] + 1:
raise ValueError("Input MST array is not a validly formatted MST array")
is_sorted = lambda x: np.all(x[:-1] <= x[1:])
if not is_sorted(L[:, 2]):
raise ValueError("Input MST array must be sorted by weight")
return _single_linkage_label(L)
# Implements MST-LINKAGE-CORE from https://arxiv.org/abs/1109.2378
def mst_linkage_core(
const float64_t [:, ::1] raw_data,
DistanceMetric64 dist_metric):
"""
Compute the necessary elements of a minimum spanning
tree for computation of single linkage clustering. This
represents the MST-LINKAGE-CORE algorithm (Figure 6) from
:arxiv:`Daniel Mullner, "Modern hierarchical, agglomerative clustering
algorithms" <1109.2378>`.
In contrast to the scipy implementation is never computes
a full distance matrix, generating distances only as they
are needed and releasing them when no longer needed.
Parameters
----------
raw_data: array of shape (n_samples, n_features)
The array of feature data to be clustered. Must be C-aligned
dist_metric: DistanceMetric64
A DistanceMetric64 object conforming to the API from
``sklearn.metrics._dist_metrics.pxd`` that will be
used to compute distances.
Returns
-------
mst_core_data: array of shape (n_samples, 3)
An array providing information from which one
can either compute an MST, or the linkage hierarchy
very efficiently. See :arxiv:`Daniel Mullner, "Modern hierarchical,
agglomerative clustering algorithms" <1109.2378>` algorithm
MST-LINKAGE-CORE for more details.
"""
cdef:
intp_t n_samples = raw_data.shape[0]
uint8_t[:] in_tree = np.zeros(n_samples, dtype=bool)
float64_t[:, ::1] result = np.zeros((n_samples - 1, 3))
intp_t current_node = 0
intp_t new_node
intp_t i
intp_t j
intp_t num_features = raw_data.shape[1]
float64_t right_value
float64_t left_value
float64_t new_distance
float64_t[:] current_distances = np.full(n_samples, INFINITY)
for i in range(n_samples - 1):
in_tree[current_node] = 1
new_distance = INFINITY
new_node = 0
for j in range(n_samples):
if in_tree[j]:
continue
right_value = current_distances[j]
left_value = dist_metric.dist(&raw_data[current_node, 0],
&raw_data[j, 0],
num_features)
if left_value < right_value:
current_distances[j] = left_value
if current_distances[j] < new_distance:
new_distance = current_distances[j]
new_node = j
result[i, 0] = current_node
result[i, 1] = new_node
result[i, 2] = new_distance
current_node = new_node
return np.array(result)

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from cython cimport floating
cdef floating _euclidean_dense_dense(
const floating*,
const floating*,
int,
bint
) noexcept nogil
cdef floating _euclidean_sparse_dense(
const floating[::1],
const int[::1],
const floating[::1],
floating,
bint
) noexcept nogil
cpdef void _relocate_empty_clusters_dense(
const floating[:, ::1],
const floating[::1],
const floating[:, ::1],
floating[:, ::1],
floating[::1],
const int[::1]
)
cpdef void _relocate_empty_clusters_sparse(
const floating[::1],
const int[::1],
const int[::1],
const floating[::1],
const floating[:, ::1],
floating[:, ::1],
floating[::1],
const int[::1]
)
cdef void _average_centers(
floating[:, ::1],
const floating[::1]
)
cdef void _center_shift(
const floating[:, ::1],
const floating[:, ::1],
floating[::1]
)

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@@ -0,0 +1,328 @@
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import numpy as np
from cython cimport floating
from cython.parallel cimport prange
from libc.math cimport sqrt
from sklearn.utils.extmath import row_norms
# Number of samples per data chunk defined as a global constant.
CHUNK_SIZE = 256
cdef floating _euclidean_dense_dense(
const floating* a, # IN
const floating* b, # IN
int n_features,
bint squared
) noexcept nogil:
"""Euclidean distance between a dense and b dense"""
cdef:
int i
int n = n_features // 4
int rem = n_features % 4
floating result = 0
# We manually unroll the loop for better cache optimization.
for i in range(n):
result += (
(a[0] - b[0]) * (a[0] - b[0]) +
(a[1] - b[1]) * (a[1] - b[1]) +
(a[2] - b[2]) * (a[2] - b[2]) +
(a[3] - b[3]) * (a[3] - b[3])
)
a += 4
b += 4
for i in range(rem):
result += (a[i] - b[i]) * (a[i] - b[i])
return result if squared else sqrt(result)
def _euclidean_dense_dense_wrapper(
const floating[::1] a,
const floating[::1] b,
bint squared
):
"""Wrapper of _euclidean_dense_dense for testing purpose"""
return _euclidean_dense_dense(&a[0], &b[0], a.shape[0], squared)
cdef floating _euclidean_sparse_dense(
const floating[::1] a_data, # IN
const int[::1] a_indices, # IN
const floating[::1] b, # IN
floating b_squared_norm,
bint squared
) noexcept nogil:
"""Euclidean distance between a sparse and b dense"""
cdef:
int nnz = a_indices.shape[0]
int i
floating tmp, bi
floating result = 0.0
for i in range(nnz):
bi = b[a_indices[i]]
tmp = a_data[i] - bi
result += tmp * tmp - bi * bi
result += b_squared_norm
if result < 0:
result = 0.0
return result if squared else sqrt(result)
def _euclidean_sparse_dense_wrapper(
const floating[::1] a_data,
const int[::1] a_indices,
const floating[::1] b,
floating b_squared_norm,
bint squared
):
"""Wrapper of _euclidean_sparse_dense for testing purpose"""
return _euclidean_sparse_dense(
a_data, a_indices, b, b_squared_norm, squared)
cpdef floating _inertia_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers, # IN
const int[::1] labels, # IN
int n_threads,
int single_label=-1,
):
"""Compute inertia for dense input data
Sum of squared distance between each sample and its assigned center.
If single_label is >= 0, the inertia is computed only for that label.
"""
cdef:
int n_samples = X.shape[0]
int n_features = X.shape[1]
int i, j
floating sq_dist = 0.0
floating inertia = 0.0
for i in prange(n_samples, nogil=True, num_threads=n_threads,
schedule='static'):
j = labels[i]
if single_label < 0 or single_label == j:
sq_dist = _euclidean_dense_dense(&X[i, 0], &centers[j, 0],
n_features, True)
inertia += sq_dist * sample_weight[i]
return inertia
cpdef floating _inertia_sparse(
X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers, # IN
const int[::1] labels, # IN
int n_threads,
int single_label=-1,
):
"""Compute inertia for sparse input data
Sum of squared distance between each sample and its assigned center.
If single_label is >= 0, the inertia is computed only for that label.
"""
cdef:
floating[::1] X_data = X.data
int[::1] X_indices = X.indices
int[::1] X_indptr = X.indptr
int n_samples = X.shape[0]
int i, j
floating sq_dist = 0.0
floating inertia = 0.0
floating[::1] centers_squared_norms = row_norms(centers, squared=True)
for i in prange(n_samples, nogil=True, num_threads=n_threads,
schedule='static'):
j = labels[i]
if single_label < 0 or single_label == j:
sq_dist = _euclidean_sparse_dense(
X_data[X_indptr[i]: X_indptr[i + 1]],
X_indices[X_indptr[i]: X_indptr[i + 1]],
centers[j], centers_squared_norms[j], True)
inertia += sq_dist * sample_weight[i]
return inertia
cpdef void _relocate_empty_clusters_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # INOUT
floating[::1] weight_in_clusters, # INOUT
const int[::1] labels # IN
):
"""Relocate centers which have no sample assigned to them."""
cdef:
int[::1] empty_clusters = np.where(np.equal(weight_in_clusters, 0))[0].astype(np.int32)
int n_empty = empty_clusters.shape[0]
if n_empty == 0:
return
cdef:
int n_features = X.shape[1]
floating[::1] distances = ((np.asarray(X) - np.asarray(centers_old)[labels])**2).sum(axis=1)
int[::1] far_from_centers = np.argpartition(distances, -n_empty)[:-n_empty-1:-1].astype(np.int32)
int new_cluster_id, old_cluster_id, far_idx, idx, k
floating weight
if np.max(distances) == 0:
# Happens when there are more clusters than non-duplicate samples. Relocating
# is pointless in this case.
return
for idx in range(n_empty):
new_cluster_id = empty_clusters[idx]
far_idx = far_from_centers[idx]
weight = sample_weight[far_idx]
old_cluster_id = labels[far_idx]
for k in range(n_features):
centers_new[old_cluster_id, k] -= X[far_idx, k] * weight
centers_new[new_cluster_id, k] = X[far_idx, k] * weight
weight_in_clusters[new_cluster_id] = weight
weight_in_clusters[old_cluster_id] -= weight
cpdef void _relocate_empty_clusters_sparse(
const floating[::1] X_data, # IN
const int[::1] X_indices, # IN
const int[::1] X_indptr, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # INOUT
floating[::1] weight_in_clusters, # INOUT
const int[::1] labels # IN
):
"""Relocate centers which have no sample assigned to them."""
cdef:
int[::1] empty_clusters = np.where(np.equal(weight_in_clusters, 0))[0].astype(np.int32)
int n_empty = empty_clusters.shape[0]
if n_empty == 0:
return
cdef:
int n_samples = X_indptr.shape[0] - 1
int i, j, k
floating[::1] distances = np.zeros(n_samples, dtype=X_data.base.dtype)
floating[::1] centers_squared_norms = row_norms(centers_old, squared=True)
for i in range(n_samples):
j = labels[i]
distances[i] = _euclidean_sparse_dense(
X_data[X_indptr[i]: X_indptr[i + 1]],
X_indices[X_indptr[i]: X_indptr[i + 1]],
centers_old[j], centers_squared_norms[j], True)
if np.max(distances) == 0:
# Happens when there are more clusters than non-duplicate samples. Relocating
# is pointless in this case.
return
cdef:
int[::1] far_from_centers = np.argpartition(distances, -n_empty)[:-n_empty-1:-1].astype(np.int32)
int new_cluster_id, old_cluster_id, far_idx, idx
floating weight
for idx in range(n_empty):
new_cluster_id = empty_clusters[idx]
far_idx = far_from_centers[idx]
weight = sample_weight[far_idx]
old_cluster_id = labels[far_idx]
for k in range(X_indptr[far_idx], X_indptr[far_idx + 1]):
centers_new[old_cluster_id, X_indices[k]] -= X_data[k] * weight
centers_new[new_cluster_id, X_indices[k]] = X_data[k] * weight
weight_in_clusters[new_cluster_id] = weight
weight_in_clusters[old_cluster_id] -= weight
cdef void _average_centers(
floating[:, ::1] centers, # INOUT
const floating[::1] weight_in_clusters # IN
):
"""Average new centers wrt weights."""
cdef:
int n_clusters = centers.shape[0]
int n_features = centers.shape[1]
int j, k
floating alpha
int argmax_weight = np.argmax(weight_in_clusters)
for j in range(n_clusters):
if weight_in_clusters[j] > 0:
alpha = 1.0 / weight_in_clusters[j]
for k in range(n_features):
centers[j, k] *= alpha
else:
# For convenience, we avoid setting empty clusters at the origin but place
# them at the location of the biggest cluster.
for k in range(n_features):
centers[j, k] = centers[argmax_weight, k]
cdef void _center_shift(
const floating[:, ::1] centers_old, # IN
const floating[:, ::1] centers_new, # IN
floating[::1] center_shift # OUT
):
"""Compute shift between old and new centers."""
cdef:
int n_clusters = centers_old.shape[0]
int n_features = centers_old.shape[1]
int j
for j in range(n_clusters):
center_shift[j] = _euclidean_dense_dense(
&centers_new[j, 0], &centers_old[j, 0], n_features, False)
def _is_same_clustering(
const int[::1] labels1,
const int[::1] labels2,
n_clusters
):
"""Check if two arrays of labels are the same up to a permutation of the labels"""
cdef int[::1] mapping = np.full(fill_value=-1, shape=(n_clusters,), dtype=np.int32)
cdef int i
for i in range(labels1.shape[0]):
if mapping[labels1[i]] == -1:
mapping[labels1[i]] = labels2[i]
elif mapping[labels1[i]] != labels2[i]:
return False
return True

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# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
from cython cimport floating
from cython.parallel import prange, parallel
from libc.stdlib cimport calloc, free
from libc.string cimport memset
from sklearn.utils._openmp_helpers cimport omp_lock_t
from sklearn.utils._openmp_helpers cimport omp_init_lock
from sklearn.utils._openmp_helpers cimport omp_destroy_lock
from sklearn.utils._openmp_helpers cimport omp_set_lock
from sklearn.utils._openmp_helpers cimport omp_unset_lock
from sklearn.utils.extmath import row_norms
from sklearn.cluster._k_means_common import CHUNK_SIZE
from sklearn.cluster._k_means_common cimport _relocate_empty_clusters_dense
from sklearn.cluster._k_means_common cimport _relocate_empty_clusters_sparse
from sklearn.cluster._k_means_common cimport _euclidean_dense_dense
from sklearn.cluster._k_means_common cimport _euclidean_sparse_dense
from sklearn.cluster._k_means_common cimport _average_centers
from sklearn.cluster._k_means_common cimport _center_shift
def init_bounds_dense(
const floating[:, ::1] X, # IN
const floating[:, ::1] centers, # IN
const floating[:, ::1] center_half_distances, # IN
int[::1] labels, # OUT
floating[::1] upper_bounds, # OUT
floating[:, ::1] lower_bounds, # OUT
int n_threads):
"""Initialize upper and lower bounds for each sample for dense input data.
Given X, centers and the pairwise distances divided by 2.0 between the
centers this calculates the upper bounds and lower bounds for each sample.
The upper bound for each sample is set to the distance between the sample
and the closest center.
The lower bound for each sample is a one-dimensional array of n_clusters.
For each sample i assume that the previously assigned cluster is c1 and the
previous closest distance is dist, for a new cluster c2, the
lower_bound[i][c2] is set to distance between the sample and this new
cluster, if and only if dist > center_half_distances[c1][c2]. This prevents
computation of unnecessary distances for each sample to the clusters that
it is unlikely to be assigned to.
Parameters
----------
X : ndarray of shape (n_samples, n_features), dtype=floating
The input data.
centers : ndarray of shape (n_clusters, n_features), dtype=floating
The cluster centers.
center_half_distances : ndarray of shape (n_clusters, n_clusters), \
dtype=floating
The half of the distance between any 2 clusters centers.
labels : ndarray of shape(n_samples), dtype=int
The label for each sample. This array is modified in place.
upper_bounds : ndarray of shape(n_samples,), dtype=floating
The upper bound on the distance between each sample and its closest
cluster center. This array is modified in place.
lower_bounds : ndarray, of shape(n_samples, n_clusters), dtype=floating
The lower bound on the distance between each sample and each cluster
center. This array is modified in place.
n_threads : int
The number of threads to be used by openmp.
"""
cdef:
int n_samples = X.shape[0]
int n_clusters = centers.shape[0]
int n_features = X.shape[1]
floating min_dist, dist
int best_cluster, i, j
for i in prange(
n_samples, num_threads=n_threads, schedule='static', nogil=True
):
best_cluster = 0
min_dist = _euclidean_dense_dense(&X[i, 0], &centers[0, 0],
n_features, False)
lower_bounds[i, 0] = min_dist
for j in range(1, n_clusters):
if min_dist > center_half_distances[best_cluster, j]:
dist = _euclidean_dense_dense(&X[i, 0], &centers[j, 0],
n_features, False)
lower_bounds[i, j] = dist
if dist < min_dist:
min_dist = dist
best_cluster = j
labels[i] = best_cluster
upper_bounds[i] = min_dist
def init_bounds_sparse(
X, # IN
const floating[:, ::1] centers, # IN
const floating[:, ::1] center_half_distances, # IN
int[::1] labels, # OUT
floating[::1] upper_bounds, # OUT
floating[:, ::1] lower_bounds, # OUT
int n_threads):
"""Initialize upper and lower bounds for each sample for sparse input data.
Given X, centers and the pairwise distances divided by 2.0 between the
centers this calculates the upper bounds and lower bounds for each sample.
The upper bound for each sample is set to the distance between the sample
and the closest center.
The lower bound for each sample is a one-dimensional array of n_clusters.
For each sample i assume that the previously assigned cluster is c1 and the
previous closest distance is dist, for a new cluster c2, the
lower_bound[i][c2] is set to distance between the sample and this new
cluster, if and only if dist > center_half_distances[c1][c2]. This prevents
computation of unnecessary distances for each sample to the clusters that
it is unlikely to be assigned to.
Parameters
----------
X : sparse matrix of shape (n_samples, n_features), dtype=floating
The input data. Must be in CSR format.
centers : ndarray of shape (n_clusters, n_features), dtype=floating
The cluster centers.
center_half_distances : ndarray of shape (n_clusters, n_clusters), \
dtype=floating
The half of the distance between any 2 clusters centers.
labels : ndarray of shape(n_samples), dtype=int
The label for each sample. This array is modified in place.
upper_bounds : ndarray of shape(n_samples,), dtype=floating
The upper bound on the distance between each sample and its closest
cluster center. This array is modified in place.
lower_bounds : ndarray of shape(n_samples, n_clusters), dtype=floating
The lower bound on the distance between each sample and each cluster
center. This array is modified in place.
n_threads : int
The number of threads to be used by openmp.
"""
cdef:
int n_samples = X.shape[0]
int n_clusters = centers.shape[0]
floating[::1] X_data = X.data
int[::1] X_indices = X.indices
int[::1] X_indptr = X.indptr
floating min_dist, dist
int best_cluster, i, j
floating[::1] centers_squared_norms = row_norms(centers, squared=True)
for i in prange(
n_samples, num_threads=n_threads, schedule='static', nogil=True
):
best_cluster = 0
min_dist = _euclidean_sparse_dense(
X_data[X_indptr[i]: X_indptr[i + 1]],
X_indices[X_indptr[i]: X_indptr[i + 1]],
centers[0], centers_squared_norms[0], False)
lower_bounds[i, 0] = min_dist
for j in range(1, n_clusters):
if min_dist > center_half_distances[best_cluster, j]:
dist = _euclidean_sparse_dense(
X_data[X_indptr[i]: X_indptr[i + 1]],
X_indices[X_indptr[i]: X_indptr[i + 1]],
centers[j], centers_squared_norms[j], False)
lower_bounds[i, j] = dist
if dist < min_dist:
min_dist = dist
best_cluster = j
labels[i] = best_cluster
upper_bounds[i] = min_dist
def elkan_iter_chunked_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_in_clusters, # OUT
const floating[:, ::1] center_half_distances, # IN
const floating[::1] distance_next_center, # IN
floating[::1] upper_bounds, # INOUT
floating[:, ::1] lower_bounds, # INOUT
int[::1] labels, # INOUT
floating[::1] center_shift, # OUT
int n_threads,
bint update_centers=True):
"""Single iteration of K-means Elkan algorithm with dense input.
Update labels and centers (inplace), for one iteration, distributed
over data chunks.
Parameters
----------
X : ndarray of shape (n_samples, n_features), dtype=floating
The observations to cluster.
sample_weight : ndarray of shape (n_samples,), dtype=floating
The weights for each observation in X.
centers_old : ndarray of shape (n_clusters, n_features), dtype=floating
Centers before previous iteration, placeholder for the centers after
previous iteration.
centers_new : ndarray of shape (n_clusters, n_features), dtype=floating
Centers after previous iteration, placeholder for the new centers
computed during this iteration.
weight_in_clusters : ndarray of shape (n_clusters,), dtype=floating
Placeholder for the sums of the weights of every observation assigned
to each center.
center_half_distances : ndarray of shape (n_clusters, n_clusters), \
dtype=floating
Half pairwise distances between centers.
distance_next_center : ndarray of shape (n_clusters,), dtype=floating
Distance between each center its closest center.
upper_bounds : ndarray of shape (n_samples,), dtype=floating
Upper bound for the distance between each sample and its center,
updated inplace.
lower_bounds : ndarray of shape (n_samples, n_clusters), dtype=floating
Lower bound for the distance between each sample and each center,
updated inplace.
labels : ndarray of shape (n_samples,), dtype=int
labels assignment.
center_shift : ndarray of shape (n_clusters,), dtype=floating
Distance between old and new centers.
n_threads : int
The number of threads to be used by openmp.
update_centers : bool
- If True, the labels and the new centers will be computed, i.e. runs
the E-step and the M-step of the algorithm.
- If False, only the labels will be computed, i.e runs the E-step of
the algorithm. This is useful especially when calling predict on a
fitted model.
"""
cdef:
int n_samples = X.shape[0]
int n_features = X.shape[1]
int n_clusters = centers_new.shape[0]
if n_samples == 0:
# An empty array was passed, do nothing and return early (before
# attempting to compute n_chunks). This can typically happen when
# calling the prediction function of a bisecting k-means model with a
# large fraction of outliers.
return
cdef:
# hard-coded number of samples per chunk. Splitting in chunks is
# necessary to get parallelism. Chunk size chosen to be same as lloyd's
int n_samples_chunk = CHUNK_SIZE if n_samples > CHUNK_SIZE else n_samples
int n_chunks = n_samples // n_samples_chunk
int n_samples_rem = n_samples % n_samples_chunk
int chunk_idx
int start, end
int i, j, k
floating *centers_new_chunk
floating *weight_in_clusters_chunk
omp_lock_t lock
# count remainder chunk in total number of chunks
n_chunks += n_samples != n_chunks * n_samples_chunk
# number of threads should not be bigger than number of chunks
n_threads = min(n_threads, n_chunks)
if update_centers:
memset(&centers_new[0, 0], 0, n_clusters * n_features * sizeof(floating))
memset(&weight_in_clusters[0], 0, n_clusters * sizeof(floating))
omp_init_lock(&lock)
with nogil, parallel(num_threads=n_threads):
# thread local buffers
centers_new_chunk = <floating*> calloc(n_clusters * n_features, sizeof(floating))
weight_in_clusters_chunk = <floating*> calloc(n_clusters, sizeof(floating))
for chunk_idx in prange(n_chunks, schedule='static'):
start = chunk_idx * n_samples_chunk
if chunk_idx == n_chunks - 1 and n_samples_rem > 0:
end = start + n_samples_rem
else:
end = start + n_samples_chunk
_update_chunk_dense(
X[start: end],
sample_weight[start: end],
centers_old,
center_half_distances,
distance_next_center,
labels[start: end],
upper_bounds[start: end],
lower_bounds[start: end],
centers_new_chunk,
weight_in_clusters_chunk,
update_centers)
# reduction from local buffers.
if update_centers:
# The lock is necessary to avoid race conditions when aggregating
# info from different thread-local buffers.
omp_set_lock(&lock)
for j in range(n_clusters):
weight_in_clusters[j] += weight_in_clusters_chunk[j]
for k in range(n_features):
centers_new[j, k] += centers_new_chunk[j * n_features + k]
omp_unset_lock(&lock)
free(centers_new_chunk)
free(weight_in_clusters_chunk)
if update_centers:
omp_destroy_lock(&lock)
_relocate_empty_clusters_dense(X, sample_weight, centers_old,
centers_new, weight_in_clusters, labels)
_average_centers(centers_new, weight_in_clusters)
_center_shift(centers_old, centers_new, center_shift)
# update lower and upper bounds
for i in range(n_samples):
upper_bounds[i] += center_shift[labels[i]]
for j in range(n_clusters):
lower_bounds[i, j] -= center_shift[j]
if lower_bounds[i, j] < 0:
lower_bounds[i, j] = 0
cdef void _update_chunk_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
const floating[:, ::1] center_half_distances, # IN
const floating[::1] distance_next_center, # IN
int[::1] labels, # INOUT
floating[::1] upper_bounds, # INOUT
floating[:, ::1] lower_bounds, # INOUT
floating *centers_new, # OUT
floating *weight_in_clusters, # OUT
bint update_centers) noexcept nogil:
"""K-means combined EM step for one dense data chunk.
Compute the partial contribution of a single data chunk to the labels and
centers.
"""
cdef:
int n_samples = labels.shape[0]
int n_clusters = centers_old.shape[0]
int n_features = centers_old.shape[1]
floating upper_bound, distance
int i, j, k, label
for i in range(n_samples):
upper_bound = upper_bounds[i]
bounds_tight = 0
label = labels[i]
# Next center is not far away from the currently assigned center.
# Sample might need to be assigned to another center.
if not distance_next_center[label] >= upper_bound:
for j in range(n_clusters):
# If this holds, then center_index is a good candidate for the
# sample to be relabelled, and we need to confirm this by
# recomputing the upper and lower bounds.
if (
j != label
and (upper_bound > lower_bounds[i, j])
and (upper_bound > center_half_distances[label, j])
):
# Recompute upper bound by calculating the actual distance
# between the sample and its current assigned center.
if not bounds_tight:
upper_bound = _euclidean_dense_dense(
&X[i, 0], &centers_old[label, 0], n_features, False)
lower_bounds[i, label] = upper_bound
bounds_tight = 1
# If the condition still holds, then compute the actual
# distance between the sample and center. If this is less
# than the previous distance, reassign label.
if (
upper_bound > lower_bounds[i, j]
or (upper_bound > center_half_distances[label, j])
):
distance = _euclidean_dense_dense(
&X[i, 0], &centers_old[j, 0], n_features, False)
lower_bounds[i, j] = distance
if distance < upper_bound:
label = j
upper_bound = distance
labels[i] = label
upper_bounds[i] = upper_bound
if update_centers:
weight_in_clusters[label] += sample_weight[i]
for k in range(n_features):
centers_new[label * n_features + k] += X[i, k] * sample_weight[i]
def elkan_iter_chunked_sparse(
X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_in_clusters, # OUT
const floating[:, ::1] center_half_distances, # IN
const floating[::1] distance_next_center, # IN
floating[::1] upper_bounds, # INOUT
floating[:, ::1] lower_bounds, # INOUT
int[::1] labels, # INOUT
floating[::1] center_shift, # OUT
int n_threads,
bint update_centers=True):
"""Single iteration of K-means Elkan algorithm with sparse input.
Update labels and centers (inplace), for one iteration, distributed
over data chunks.
Parameters
----------
X : sparse matrix of shape (n_samples, n_features)
The observations to cluster. Must be in CSR format.
sample_weight : ndarray of shape (n_samples,), dtype=floating
The weights for each observation in X.
centers_old : ndarray of shape (n_clusters, n_features), dtype=floating
Centers before previous iteration, placeholder for the centers after
previous iteration.
centers_new : ndarray of shape (n_clusters, n_features), dtype=floating
Centers after previous iteration, placeholder for the new centers
computed during this iteration.
weight_in_clusters : ndarray of shape (n_clusters,), dtype=floating
Placeholder for the sums of the weights of every observation assigned
to each center.
center_half_distances : ndarray of shape (n_clusters, n_clusters), \
dtype=floating
Half pairwise distances between centers.
distance_next_center : ndarray of shape (n_clusters,), dtype=floating
Distance between each center its closest center.
upper_bounds : ndarray of shape (n_samples,), dtype=floating
Upper bound for the distance between each sample and its center,
updated inplace.
lower_bounds : ndarray of shape (n_samples, n_clusters), dtype=floating
Lower bound for the distance between each sample and each center,
updated inplace.
labels : ndarray of shape (n_samples,), dtype=int
labels assignment.
center_shift : ndarray of shape (n_clusters,), dtype=floating
Distance between old and new centers.
n_threads : int
The number of threads to be used by openmp.
update_centers : bool
- If True, the labels and the new centers will be computed, i.e. runs
the E-step and the M-step of the algorithm.
- If False, only the labels will be computed, i.e runs the E-step of
the algorithm. This is useful especially when calling predict on a
fitted model.
"""
cdef:
int n_samples = X.shape[0]
int n_features = X.shape[1]
int n_clusters = centers_new.shape[0]
if n_samples == 0:
# An empty array was passed, do nothing and return early (before
# attempting to compute n_chunks). This can typically happen when
# calling the prediction function of a bisecting k-means model with a
# large fraction of outliers.
return
cdef:
floating[::1] X_data = X.data
int[::1] X_indices = X.indices
int[::1] X_indptr = X.indptr
# hard-coded number of samples per chunk. Splitting in chunks is
# necessary to get parallelism. Chunk size chosen to be same as lloyd's
int n_samples_chunk = CHUNK_SIZE if n_samples > CHUNK_SIZE else n_samples
int n_chunks = n_samples // n_samples_chunk
int n_samples_rem = n_samples % n_samples_chunk
int chunk_idx
int start, end
int i, j, k
floating[::1] centers_squared_norms = row_norms(centers_old, squared=True)
floating *centers_new_chunk
floating *weight_in_clusters_chunk
omp_lock_t lock
# count remainder chunk in total number of chunks
n_chunks += n_samples != n_chunks * n_samples_chunk
# number of threads should not be bigger than number of chunks
n_threads = min(n_threads, n_chunks)
if update_centers:
memset(&centers_new[0, 0], 0, n_clusters * n_features * sizeof(floating))
memset(&weight_in_clusters[0], 0, n_clusters * sizeof(floating))
omp_init_lock(&lock)
with nogil, parallel(num_threads=n_threads):
# thread local buffers
centers_new_chunk = <floating*> calloc(n_clusters * n_features, sizeof(floating))
weight_in_clusters_chunk = <floating*> calloc(n_clusters, sizeof(floating))
for chunk_idx in prange(n_chunks, schedule='static'):
start = chunk_idx * n_samples_chunk
if chunk_idx == n_chunks - 1 and n_samples_rem > 0:
end = start + n_samples_rem
else:
end = start + n_samples_chunk
_update_chunk_sparse(
X_data[X_indptr[start]: X_indptr[end]],
X_indices[X_indptr[start]: X_indptr[end]],
X_indptr[start: end+1],
sample_weight[start: end],
centers_old,
centers_squared_norms,
center_half_distances,
distance_next_center,
labels[start: end],
upper_bounds[start: end],
lower_bounds[start: end],
centers_new_chunk,
weight_in_clusters_chunk,
update_centers)
# reduction from local buffers.
if update_centers:
# The lock is necessary to avoid race conditions when aggregating
# info from different thread-local buffers.
omp_set_lock(&lock)
for j in range(n_clusters):
weight_in_clusters[j] += weight_in_clusters_chunk[j]
for k in range(n_features):
centers_new[j, k] += centers_new_chunk[j * n_features + k]
omp_unset_lock(&lock)
free(centers_new_chunk)
free(weight_in_clusters_chunk)
if update_centers:
omp_destroy_lock(&lock)
_relocate_empty_clusters_sparse(
X_data, X_indices, X_indptr, sample_weight,
centers_old, centers_new, weight_in_clusters, labels)
_average_centers(centers_new, weight_in_clusters)
_center_shift(centers_old, centers_new, center_shift)
# update lower and upper bounds
for i in range(n_samples):
upper_bounds[i] += center_shift[labels[i]]
for j in range(n_clusters):
lower_bounds[i, j] -= center_shift[j]
if lower_bounds[i, j] < 0:
lower_bounds[i, j] = 0
cdef void _update_chunk_sparse(
const floating[::1] X_data, # IN
const int[::1] X_indices, # IN
const int[::1] X_indptr, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
const floating[::1] centers_squared_norms, # IN
const floating[:, ::1] center_half_distances, # IN
const floating[::1] distance_next_center, # IN
int[::1] labels, # INOUT
floating[::1] upper_bounds, # INOUT
floating[:, ::1] lower_bounds, # INOUT
floating *centers_new, # OUT
floating *weight_in_clusters, # OUT
bint update_centers) noexcept nogil:
"""K-means combined EM step for one sparse data chunk.
Compute the partial contribution of a single data chunk to the labels and
centers.
"""
cdef:
int n_samples = labels.shape[0]
int n_clusters = centers_old.shape[0]
int n_features = centers_old.shape[1]
floating upper_bound, distance
int i, j, k, label
int s = X_indptr[0]
for i in range(n_samples):
upper_bound = upper_bounds[i]
bounds_tight = 0
label = labels[i]
# Next center is not far away from the currently assigned center.
# Sample might need to be assigned to another center.
if not distance_next_center[label] >= upper_bound:
for j in range(n_clusters):
# If this holds, then center_index is a good candidate for the
# sample to be relabelled, and we need to confirm this by
# recomputing the upper and lower bounds.
if (
j != label
and (upper_bound > lower_bounds[i, j])
and (upper_bound > center_half_distances[label, j])
):
# Recompute upper bound by calculating the actual distance
# between the sample and its current assigned center.
if not bounds_tight:
upper_bound = _euclidean_sparse_dense(
X_data[X_indptr[i] - s: X_indptr[i + 1] - s],
X_indices[X_indptr[i] - s: X_indptr[i + 1] - s],
centers_old[label], centers_squared_norms[label], False)
lower_bounds[i, label] = upper_bound
bounds_tight = 1
# If the condition still holds, then compute the actual
# distance between the sample and center. If this is less
# than the previous distance, reassign label.
if (
upper_bound > lower_bounds[i, j]
or (upper_bound > center_half_distances[label, j])
):
distance = _euclidean_sparse_dense(
X_data[X_indptr[i] - s: X_indptr[i + 1] - s],
X_indices[X_indptr[i] - s: X_indptr[i + 1] - s],
centers_old[j], centers_squared_norms[j], False)
lower_bounds[i, j] = distance
if distance < upper_bound:
label = j
upper_bound = distance
labels[i] = label
upper_bounds[i] = upper_bound
if update_centers:
weight_in_clusters[label] += sample_weight[i]
for k in range(X_indptr[i] - s, X_indptr[i + 1] - s):
centers_new[label * n_features + X_indices[k]] += X_data[k] * sample_weight[i]

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# Licence: BSD 3 clause
from cython cimport floating
from cython.parallel import prange, parallel
from libc.stdlib cimport malloc, calloc, free
from libc.string cimport memset
from libc.float cimport DBL_MAX, FLT_MAX
from sklearn.utils._openmp_helpers cimport omp_lock_t
from sklearn.utils._openmp_helpers cimport omp_init_lock
from sklearn.utils._openmp_helpers cimport omp_destroy_lock
from sklearn.utils._openmp_helpers cimport omp_set_lock
from sklearn.utils._openmp_helpers cimport omp_unset_lock
from sklearn.utils.extmath import row_norms
from sklearn.utils._cython_blas cimport _gemm
from sklearn.utils._cython_blas cimport RowMajor, Trans, NoTrans
from sklearn.cluster._k_means_common import CHUNK_SIZE
from sklearn.cluster._k_means_common cimport _relocate_empty_clusters_dense
from sklearn.cluster._k_means_common cimport _relocate_empty_clusters_sparse
from sklearn.cluster._k_means_common cimport _average_centers, _center_shift
def lloyd_iter_chunked_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_in_clusters, # OUT
int[::1] labels, # OUT
floating[::1] center_shift, # OUT
int n_threads,
bint update_centers=True):
"""Single iteration of K-means lloyd algorithm with dense input.
Update labels and centers (inplace), for one iteration, distributed
over data chunks.
Parameters
----------
X : ndarray of shape (n_samples, n_features), dtype=floating
The observations to cluster.
sample_weight : ndarray of shape (n_samples,), dtype=floating
The weights for each observation in X.
centers_old : ndarray of shape (n_clusters, n_features), dtype=floating
Centers before previous iteration, placeholder for the centers after
previous iteration.
centers_new : ndarray of shape (n_clusters, n_features), dtype=floating
Centers after previous iteration, placeholder for the new centers
computed during this iteration. `centers_new` can be `None` if
`update_centers` is False.
weight_in_clusters : ndarray of shape (n_clusters,), dtype=floating
Placeholder for the sums of the weights of every observation assigned
to each center. `weight_in_clusters` can be `None` if `update_centers`
is False.
labels : ndarray of shape (n_samples,), dtype=int
labels assignment.
center_shift : ndarray of shape (n_clusters,), dtype=floating
Distance between old and new centers.
n_threads : int
The number of threads to be used by openmp.
update_centers : bool
- If True, the labels and the new centers will be computed, i.e. runs
the E-step and the M-step of the algorithm.
- If False, only the labels will be computed, i.e runs the E-step of
the algorithm. This is useful especially when calling predict on a
fitted model.
"""
cdef:
int n_samples = X.shape[0]
int n_features = X.shape[1]
int n_clusters = centers_old.shape[0]
if n_samples == 0:
# An empty array was passed, do nothing and return early (before
# attempting to compute n_chunks). This can typically happen when
# calling the prediction function of a bisecting k-means model with a
# large fraction of outliers.
return
cdef:
# hard-coded number of samples per chunk. Appeared to be close to
# optimal in all situations.
int n_samples_chunk = CHUNK_SIZE if n_samples > CHUNK_SIZE else n_samples
int n_chunks = n_samples // n_samples_chunk
int n_samples_rem = n_samples % n_samples_chunk
int chunk_idx
int start, end
int j, k
floating[::1] centers_squared_norms = row_norms(centers_old, squared=True)
floating *centers_new_chunk
floating *weight_in_clusters_chunk
floating *pairwise_distances_chunk
omp_lock_t lock
# count remainder chunk in total number of chunks
n_chunks += n_samples != n_chunks * n_samples_chunk
# number of threads should not be bigger than number of chunks
n_threads = min(n_threads, n_chunks)
if update_centers:
memset(&centers_new[0, 0], 0, n_clusters * n_features * sizeof(floating))
memset(&weight_in_clusters[0], 0, n_clusters * sizeof(floating))
omp_init_lock(&lock)
with nogil, parallel(num_threads=n_threads):
# thread local buffers
centers_new_chunk = <floating*> calloc(n_clusters * n_features, sizeof(floating))
weight_in_clusters_chunk = <floating*> calloc(n_clusters, sizeof(floating))
pairwise_distances_chunk = <floating*> malloc(n_samples_chunk * n_clusters * sizeof(floating))
for chunk_idx in prange(n_chunks, schedule='static'):
start = chunk_idx * n_samples_chunk
if chunk_idx == n_chunks - 1 and n_samples_rem > 0:
end = start + n_samples_rem
else:
end = start + n_samples_chunk
_update_chunk_dense(
X[start: end],
sample_weight[start: end],
centers_old,
centers_squared_norms,
labels[start: end],
centers_new_chunk,
weight_in_clusters_chunk,
pairwise_distances_chunk,
update_centers)
# reduction from local buffers.
if update_centers:
# The lock is necessary to avoid race conditions when aggregating
# info from different thread-local buffers.
omp_set_lock(&lock)
for j in range(n_clusters):
weight_in_clusters[j] += weight_in_clusters_chunk[j]
for k in range(n_features):
centers_new[j, k] += centers_new_chunk[j * n_features + k]
omp_unset_lock(&lock)
free(centers_new_chunk)
free(weight_in_clusters_chunk)
free(pairwise_distances_chunk)
if update_centers:
omp_destroy_lock(&lock)
_relocate_empty_clusters_dense(
X, sample_weight, centers_old, centers_new, weight_in_clusters, labels
)
_average_centers(centers_new, weight_in_clusters)
_center_shift(centers_old, centers_new, center_shift)
cdef void _update_chunk_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
const floating[::1] centers_squared_norms, # IN
int[::1] labels, # OUT
floating *centers_new, # OUT
floating *weight_in_clusters, # OUT
floating *pairwise_distances, # OUT
bint update_centers) noexcept nogil:
"""K-means combined EM step for one dense data chunk.
Compute the partial contribution of a single data chunk to the labels and
centers.
"""
cdef:
int n_samples = labels.shape[0]
int n_clusters = centers_old.shape[0]
int n_features = centers_old.shape[1]
floating sq_dist, min_sq_dist
int i, j, k, label
# Instead of computing the full pairwise squared distances matrix,
# ||X - C||² = ||X||² - 2 X.C^T + ||C||², we only need to store
# the - 2 X.C^T + ||C||² term since the argmin for a given sample only
# depends on the centers.
# pairwise_distances = ||C||²
for i in range(n_samples):
for j in range(n_clusters):
pairwise_distances[i * n_clusters + j] = centers_squared_norms[j]
# pairwise_distances += -2 * X.dot(C.T)
_gemm(RowMajor, NoTrans, Trans, n_samples, n_clusters, n_features,
-2.0, &X[0, 0], n_features, &centers_old[0, 0], n_features,
1.0, pairwise_distances, n_clusters)
for i in range(n_samples):
min_sq_dist = pairwise_distances[i * n_clusters]
label = 0
for j in range(1, n_clusters):
sq_dist = pairwise_distances[i * n_clusters + j]
if sq_dist < min_sq_dist:
min_sq_dist = sq_dist
label = j
labels[i] = label
if update_centers:
weight_in_clusters[label] += sample_weight[i]
for k in range(n_features):
centers_new[label * n_features + k] += X[i, k] * sample_weight[i]
def lloyd_iter_chunked_sparse(
X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_in_clusters, # OUT
int[::1] labels, # OUT
floating[::1] center_shift, # OUT
int n_threads,
bint update_centers=True):
"""Single iteration of K-means lloyd algorithm with sparse input.
Update labels and centers (inplace), for one iteration, distributed
over data chunks.
Parameters
----------
X : sparse matrix of shape (n_samples, n_features), dtype=floating
The observations to cluster. Must be in CSR format.
sample_weight : ndarray of shape (n_samples,), dtype=floating
The weights for each observation in X.
centers_old : ndarray of shape (n_clusters, n_features), dtype=floating
Centers before previous iteration, placeholder for the centers after
previous iteration.
centers_new : ndarray of shape (n_clusters, n_features), dtype=floating
Centers after previous iteration, placeholder for the new centers
computed during this iteration. `centers_new` can be `None` if
`update_centers` is False.
weight_in_clusters : ndarray of shape (n_clusters,), dtype=floating
Placeholder for the sums of the weights of every observation assigned
to each center. `weight_in_clusters` can be `None` if `update_centers`
is False.
labels : ndarray of shape (n_samples,), dtype=int
labels assignment.
center_shift : ndarray of shape (n_clusters,), dtype=floating
Distance between old and new centers.
n_threads : int
The number of threads to be used by openmp.
update_centers : bool
- If True, the labels and the new centers will be computed, i.e. runs
the E-step and the M-step of the algorithm.
- If False, only the labels will be computed, i.e runs the E-step of
the algorithm. This is useful especially when calling predict on a
fitted model.
"""
cdef:
int n_samples = X.shape[0]
int n_features = X.shape[1]
int n_clusters = centers_old.shape[0]
if n_samples == 0:
# An empty array was passed, do nothing and return early (before
# attempting to compute n_chunks). This can typically happen when
# calling the prediction function of a bisecting k-means model with a
# large fraction of outliers.
return
cdef:
# Choose same as for dense. Does not have the same impact since with
# sparse data the pairwise distances matrix is not precomputed.
# However, splitting in chunks is necessary to get parallelism.
int n_samples_chunk = CHUNK_SIZE if n_samples > CHUNK_SIZE else n_samples
int n_chunks = n_samples // n_samples_chunk
int n_samples_rem = n_samples % n_samples_chunk
int chunk_idx
int start = 0, end = 0
int j, k
floating[::1] X_data = X.data
int[::1] X_indices = X.indices
int[::1] X_indptr = X.indptr
floating[::1] centers_squared_norms = row_norms(centers_old, squared=True)
floating *centers_new_chunk
floating *weight_in_clusters_chunk
omp_lock_t lock
# count remainder chunk in total number of chunks
n_chunks += n_samples != n_chunks * n_samples_chunk
# number of threads should not be bigger than number of chunks
n_threads = min(n_threads, n_chunks)
if update_centers:
memset(&centers_new[0, 0], 0, n_clusters * n_features * sizeof(floating))
memset(&weight_in_clusters[0], 0, n_clusters * sizeof(floating))
omp_init_lock(&lock)
with nogil, parallel(num_threads=n_threads):
# thread local buffers
centers_new_chunk = <floating*> calloc(n_clusters * n_features, sizeof(floating))
weight_in_clusters_chunk = <floating*> calloc(n_clusters, sizeof(floating))
for chunk_idx in prange(n_chunks, schedule='static'):
start = chunk_idx * n_samples_chunk
if chunk_idx == n_chunks - 1 and n_samples_rem > 0:
end = start + n_samples_rem
else:
end = start + n_samples_chunk
_update_chunk_sparse(
X_data[X_indptr[start]: X_indptr[end]],
X_indices[X_indptr[start]: X_indptr[end]],
X_indptr[start: end+1],
sample_weight[start: end],
centers_old,
centers_squared_norms,
labels[start: end],
centers_new_chunk,
weight_in_clusters_chunk,
update_centers)
# reduction from local buffers.
if update_centers:
# The lock is necessary to avoid race conditions when aggregating
# info from different thread-local buffers.
omp_set_lock(&lock)
for j in range(n_clusters):
weight_in_clusters[j] += weight_in_clusters_chunk[j]
for k in range(n_features):
centers_new[j, k] += centers_new_chunk[j * n_features + k]
omp_unset_lock(&lock)
free(centers_new_chunk)
free(weight_in_clusters_chunk)
if update_centers:
omp_destroy_lock(&lock)
_relocate_empty_clusters_sparse(
X_data, X_indices, X_indptr, sample_weight,
centers_old, centers_new, weight_in_clusters, labels)
_average_centers(centers_new, weight_in_clusters)
_center_shift(centers_old, centers_new, center_shift)
cdef void _update_chunk_sparse(
const floating[::1] X_data, # IN
const int[::1] X_indices, # IN
const int[::1] X_indptr, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
const floating[::1] centers_squared_norms, # IN
int[::1] labels, # OUT
floating *centers_new, # OUT
floating *weight_in_clusters, # OUT
bint update_centers) noexcept nogil:
"""K-means combined EM step for one sparse data chunk.
Compute the partial contribution of a single data chunk to the labels and
centers.
"""
cdef:
int n_samples = labels.shape[0]
int n_clusters = centers_old.shape[0]
int n_features = centers_old.shape[1]
floating sq_dist, min_sq_dist
int i, j, k, label
floating max_floating = FLT_MAX if floating is float else DBL_MAX
int s = X_indptr[0]
# XXX Precompute the pairwise distances matrix is not worth for sparse
# currently. Should be tested when BLAS (sparse x dense) matrix
# multiplication is available.
for i in range(n_samples):
min_sq_dist = max_floating
label = 0
for j in range(n_clusters):
sq_dist = 0.0
for k in range(X_indptr[i] - s, X_indptr[i + 1] - s):
sq_dist += centers_old[j, X_indices[k]] * X_data[k]
# Instead of computing the full squared distance with each cluster,
# ||X - C||² = ||X||² - 2 X.C^T + ||C||², we only need to compute
# the - 2 X.C^T + ||C||² term since the argmin for a given sample
# only depends on the centers C.
sq_dist = centers_squared_norms[j] -2 * sq_dist
if sq_dist < min_sq_dist:
min_sq_dist = sq_dist
label = j
labels[i] = label
if update_centers:
weight_in_clusters[label] += sample_weight[i]
for k in range(X_indptr[i] - s, X_indptr[i + 1] - s):
centers_new[label * n_features + X_indices[k]] += X_data[k] * sample_weight[i]

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from cython cimport floating
from cython.parallel cimport parallel, prange
from libc.stdlib cimport malloc, free
def _minibatch_update_dense(
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_sums, # INOUT
const int[::1] labels, # IN
int n_threads):
"""Update of the centers for dense MiniBatchKMeans.
Parameters
----------
X : ndarray of shape (n_samples, n_features), dtype=floating
The observations to cluster.
sample_weight : ndarray of shape (n_samples,), dtype=floating
The weights for each observation in X.
centers_old : ndarray of shape (n_clusters, n_features), dtype=floating
Centers before previous iteration, placeholder for the centers after
previous iteration.
centers_new : ndarray of shape (n_clusters, n_features), dtype=floating
Centers after previous iteration, placeholder for the new centers
computed during this iteration.
weight_sums : ndarray of shape (n_clusters,), dtype=floating
Current sums of the accumulated weights for each center.
labels : ndarray of shape (n_samples,), dtype=int
labels assignment.
n_threads : int
The number of threads to be used by openmp.
"""
cdef:
int n_samples = X.shape[0]
int n_clusters = centers_old.shape[0]
int cluster_idx
int *indices
with nogil, parallel(num_threads=n_threads):
indices = <int*> malloc(n_samples * sizeof(int))
for cluster_idx in prange(n_clusters, schedule="static"):
update_center_dense(cluster_idx, X, sample_weight,
centers_old, centers_new, weight_sums, labels,
indices)
free(indices)
cdef void update_center_dense(
int cluster_idx,
const floating[:, ::1] X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_sums, # INOUT
const int[::1] labels, # IN
int *indices) noexcept nogil: # TMP
"""Update of a single center for dense MinibatchKMeans"""
cdef:
int n_samples = sample_weight.shape[0]
int n_features = centers_old.shape[1]
floating alpha
int n_indices
int k, sample_idx, feature_idx
floating wsum = 0
# indices = np.where(labels == cluster_idx)[0]
k = 0
for sample_idx in range(n_samples):
if labels[sample_idx] == cluster_idx:
indices[k] = sample_idx
wsum += sample_weight[sample_idx]
k += 1
n_indices = k
if wsum > 0:
# Undo the previous count-based scaling for this cluster center
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] = centers_old[cluster_idx, feature_idx] * weight_sums[cluster_idx]
# Update cluster with new point members
for k in range(n_indices):
sample_idx = indices[k]
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] += X[sample_idx, feature_idx] * sample_weight[sample_idx]
# Update the count statistics for this center
weight_sums[cluster_idx] += wsum
# Rescale to compute mean of all points (old and new)
alpha = 1 / weight_sums[cluster_idx]
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] *= alpha
else:
# No sample was assigned to this cluster in this batch of data
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] = centers_old[cluster_idx, feature_idx]
def _minibatch_update_sparse(
X, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_sums, # INOUT
const int[::1] labels, # IN
int n_threads):
"""Update of the centers for sparse MiniBatchKMeans.
Parameters
----------
X : sparse matrix of shape (n_samples, n_features), dtype=floating
The observations to cluster. Must be in CSR format.
sample_weight : ndarray of shape (n_samples,), dtype=floating
The weights for each observation in X.
centers_old : ndarray of shape (n_clusters, n_features), dtype=floating
Centers before previous iteration, placeholder for the centers after
previous iteration.
centers_new : ndarray of shape (n_clusters, n_features), dtype=floating
Centers after previous iteration, placeholder for the new centers
computed during this iteration.
weight_sums : ndarray of shape (n_clusters,), dtype=floating
Current sums of the accumulated weights for each center.
labels : ndarray of shape (n_samples,), dtype=int
labels assignment.
n_threads : int
The number of threads to be used by openmp.
"""
cdef:
floating[::1] X_data = X.data
int[::1] X_indices = X.indices
int[::1] X_indptr = X.indptr
int n_samples = X.shape[0]
int n_clusters = centers_old.shape[0]
int cluster_idx
int *indices
with nogil, parallel(num_threads=n_threads):
indices = <int*> malloc(n_samples * sizeof(int))
for cluster_idx in prange(n_clusters, schedule="static"):
update_center_sparse(cluster_idx, X_data, X_indices, X_indptr,
sample_weight, centers_old, centers_new,
weight_sums, labels, indices)
free(indices)
cdef void update_center_sparse(
int cluster_idx,
const floating[::1] X_data, # IN
const int[::1] X_indices, # IN
const int[::1] X_indptr, # IN
const floating[::1] sample_weight, # IN
const floating[:, ::1] centers_old, # IN
floating[:, ::1] centers_new, # OUT
floating[::1] weight_sums, # INOUT
const int[::1] labels, # IN
int *indices) noexcept nogil: # TMP
"""Update of a single center for sparse MinibatchKMeans"""
cdef:
int n_samples = sample_weight.shape[0]
int n_features = centers_old.shape[1]
floating alpha
int n_indices
int k, sample_idx, feature_idx
floating wsum = 0
# indices = np.where(labels == cluster_idx)[0]
k = 0
for sample_idx in range(n_samples):
if labels[sample_idx] == cluster_idx:
indices[k] = sample_idx
wsum += sample_weight[sample_idx]
k += 1
n_indices = k
if wsum > 0:
# Undo the previous count-based scaling for this cluster center:
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] = centers_old[cluster_idx, feature_idx] * weight_sums[cluster_idx]
# Update cluster with new point members
for k in range(n_indices):
sample_idx = indices[k]
for feature_idx in range(X_indptr[sample_idx], X_indptr[sample_idx + 1]):
centers_new[cluster_idx, X_indices[feature_idx]] += X_data[feature_idx] * sample_weight[sample_idx]
# Update the count statistics for this center
weight_sums[cluster_idx] += wsum
# Rescale to compute mean of all points (old and new)
alpha = 1 / weight_sums[cluster_idx]
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] *= alpha
else:
# No sample was assigned to this cluster in this batch of data
for feature_idx in range(n_features):
centers_new[cluster_idx, feature_idx] = centers_old[cluster_idx, feature_idx]

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"""Mean shift clustering algorithm.
Mean shift clustering aims to discover *blobs* in a smooth density of
samples. It is a centroid based algorithm, which works by updating candidates
for centroids to be the mean of the points within a given region. These
candidates are then filtered in a post-processing stage to eliminate
near-duplicates to form the final set of centroids.
Seeding is performed using a binning technique for scalability.
"""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
from collections import defaultdict
from numbers import Integral, Real
import numpy as np
from sklearn._config import config_context
from sklearn.base import BaseEstimator, ClusterMixin, _fit_context
from sklearn.metrics.pairwise import pairwise_distances_argmin
from sklearn.neighbors import NearestNeighbors
from sklearn.utils import check_array, check_random_state, gen_batches
from sklearn.utils._param_validation import Interval, validate_params
from sklearn.utils.parallel import Parallel, delayed
from sklearn.utils.validation import check_is_fitted, validate_data
@validate_params(
{
"X": ["array-like"],
"quantile": [Interval(Real, 0, 1, closed="both")],
"n_samples": [Interval(Integral, 1, None, closed="left"), None],
"random_state": ["random_state"],
"n_jobs": [Integral, None],
},
prefer_skip_nested_validation=True,
)
def estimate_bandwidth(X, *, quantile=0.3, n_samples=None, random_state=0, n_jobs=None):
"""Estimate the bandwidth to use with the mean-shift algorithm.
This function takes time at least quadratic in `n_samples`. For large
datasets, it is wise to subsample by setting `n_samples`. Alternatively,
the parameter `bandwidth` can be set to a small value without estimating
it.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Input points.
quantile : float, default=0.3
Should be between [0, 1]
0.5 means that the median of all pairwise distances is used.
n_samples : int, default=None
The number of samples to use. If not given, all samples are used.
random_state : int, RandomState instance, default=None
The generator used to randomly select the samples from input points
for bandwidth estimation. Use an int to make the randomness
deterministic.
See :term:`Glossary <random_state>`.
n_jobs : int, default=None
The number of parallel jobs to run for neighbors search.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
Returns
-------
bandwidth : float
The bandwidth parameter.
Examples
--------
>>> import numpy as np
>>> from sklearn.cluster import estimate_bandwidth
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> estimate_bandwidth(X, quantile=0.5)
np.float64(1.61)
"""
X = check_array(X)
random_state = check_random_state(random_state)
if n_samples is not None:
idx = random_state.permutation(X.shape[0])[:n_samples]
X = X[idx]
n_neighbors = int(X.shape[0] * quantile)
if n_neighbors < 1: # cannot fit NearestNeighbors with n_neighbors = 0
n_neighbors = 1
nbrs = NearestNeighbors(n_neighbors=n_neighbors, n_jobs=n_jobs)
nbrs.fit(X)
bandwidth = 0.0
for batch in gen_batches(len(X), 500):
d, _ = nbrs.kneighbors(X[batch, :], return_distance=True)
bandwidth += np.max(d, axis=1).sum()
return bandwidth / X.shape[0]
# separate function for each seed's iterative loop
def _mean_shift_single_seed(my_mean, X, nbrs, max_iter):
# For each seed, climb gradient until convergence or max_iter
bandwidth = nbrs.get_params()["radius"]
stop_thresh = 1e-3 * bandwidth # when mean has converged
completed_iterations = 0
while True:
# Find mean of points within bandwidth
i_nbrs = nbrs.radius_neighbors([my_mean], bandwidth, return_distance=False)[0]
points_within = X[i_nbrs]
if len(points_within) == 0:
break # Depending on seeding strategy this condition may occur
my_old_mean = my_mean # save the old mean
my_mean = np.mean(points_within, axis=0)
# If converged or at max_iter, adds the cluster
if (
np.linalg.norm(my_mean - my_old_mean) <= stop_thresh
or completed_iterations == max_iter
):
break
completed_iterations += 1
return tuple(my_mean), len(points_within), completed_iterations
@validate_params(
{"X": ["array-like"]},
prefer_skip_nested_validation=False,
)
def mean_shift(
X,
*,
bandwidth=None,
seeds=None,
bin_seeding=False,
min_bin_freq=1,
cluster_all=True,
max_iter=300,
n_jobs=None,
):
"""Perform mean shift clustering of data using a flat kernel.
Read more in the :ref:`User Guide <mean_shift>`.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Input data.
bandwidth : float, default=None
Kernel bandwidth. If not None, must be in the range [0, +inf).
If None, the bandwidth is determined using a heuristic based on
the median of all pairwise distances. This will take quadratic time in
the number of samples. The sklearn.cluster.estimate_bandwidth function
can be used to do this more efficiently.
seeds : array-like of shape (n_seeds, n_features) or None
Point used as initial kernel locations. If None and bin_seeding=False,
each data point is used as a seed. If None and bin_seeding=True,
see bin_seeding.
bin_seeding : bool, default=False
If true, initial kernel locations are not locations of all
points, but rather the location of the discretized version of
points, where points are binned onto a grid whose coarseness
corresponds to the bandwidth. Setting this option to True will speed
up the algorithm because fewer seeds will be initialized.
Ignored if seeds argument is not None.
min_bin_freq : int, default=1
To speed up the algorithm, accept only those bins with at least
min_bin_freq points as seeds.
cluster_all : bool, default=True
If true, then all points are clustered, even those orphans that are
not within any kernel. Orphans are assigned to the nearest kernel.
If false, then orphans are given cluster label -1.
max_iter : int, default=300
Maximum number of iterations, per seed point before the clustering
operation terminates (for that seed point), if has not converged yet.
n_jobs : int, default=None
The number of jobs to use for the computation. The following tasks benefit
from the parallelization:
- The search of nearest neighbors for bandwidth estimation and label
assignments. See the details in the docstring of the
``NearestNeighbors`` class.
- Hill-climbing optimization for all seeds.
See :term:`Glossary <n_jobs>` for more details.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
.. versionadded:: 0.17
Parallel Execution using *n_jobs*.
Returns
-------
cluster_centers : ndarray of shape (n_clusters, n_features)
Coordinates of cluster centers.
labels : ndarray of shape (n_samples,)
Cluster labels for each point.
Notes
-----
For a usage example, see
:ref:`sphx_glr_auto_examples_cluster_plot_mean_shift.py`.
Examples
--------
>>> import numpy as np
>>> from sklearn.cluster import mean_shift
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> cluster_centers, labels = mean_shift(X, bandwidth=2)
>>> cluster_centers
array([[3.33, 6. ],
[1.33, 0.66]])
>>> labels
array([1, 1, 1, 0, 0, 0])
"""
model = MeanShift(
bandwidth=bandwidth,
seeds=seeds,
min_bin_freq=min_bin_freq,
bin_seeding=bin_seeding,
cluster_all=cluster_all,
n_jobs=n_jobs,
max_iter=max_iter,
).fit(X)
return model.cluster_centers_, model.labels_
def get_bin_seeds(X, bin_size, min_bin_freq=1):
"""Find seeds for mean_shift.
Finds seeds by first binning data onto a grid whose lines are
spaced bin_size apart, and then choosing those bins with at least
min_bin_freq points.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Input points, the same points that will be used in mean_shift.
bin_size : float
Controls the coarseness of the binning. Smaller values lead
to more seeding (which is computationally more expensive). If you're
not sure how to set this, set it to the value of the bandwidth used
in clustering.mean_shift.
min_bin_freq : int, default=1
Only bins with at least min_bin_freq will be selected as seeds.
Raising this value decreases the number of seeds found, which
makes mean_shift computationally cheaper.
Returns
-------
bin_seeds : array-like of shape (n_samples, n_features)
Points used as initial kernel positions in clustering.mean_shift.
"""
if bin_size == 0:
return X
# Bin points
bin_sizes = defaultdict(int)
for point in X:
binned_point = np.round(point / bin_size)
bin_sizes[tuple(binned_point)] += 1
# Select only those bins as seeds which have enough members
bin_seeds = np.array(
[point for point, freq in bin_sizes.items() if freq >= min_bin_freq],
dtype=np.float32,
)
if len(bin_seeds) == len(X):
warnings.warn(
"Binning data failed with provided bin_size=%f, using data points as seeds."
% bin_size
)
return X
bin_seeds = bin_seeds * bin_size
return bin_seeds
class MeanShift(ClusterMixin, BaseEstimator):
"""Mean shift clustering using a flat kernel.
Mean shift clustering aims to discover "blobs" in a smooth density of
samples. It is a centroid-based algorithm, which works by updating
candidates for centroids to be the mean of the points within a given
region. These candidates are then filtered in a post-processing stage to
eliminate near-duplicates to form the final set of centroids.
Seeding is performed using a binning technique for scalability.
For an example of how to use MeanShift clustering, refer to:
:ref:`sphx_glr_auto_examples_cluster_plot_mean_shift.py`.
Read more in the :ref:`User Guide <mean_shift>`.
Parameters
----------
bandwidth : float, default=None
Bandwidth used in the flat kernel.
If not given, the bandwidth is estimated using
sklearn.cluster.estimate_bandwidth; see the documentation for that
function for hints on scalability (see also the Notes, below).
seeds : array-like of shape (n_samples, n_features), default=None
Seeds used to initialize kernels. If not set,
the seeds are calculated by clustering.get_bin_seeds
with bandwidth as the grid size and default values for
other parameters.
bin_seeding : bool, default=False
If true, initial kernel locations are not locations of all
points, but rather the location of the discretized version of
points, where points are binned onto a grid whose coarseness
corresponds to the bandwidth. Setting this option to True will speed
up the algorithm because fewer seeds will be initialized.
The default value is False.
Ignored if seeds argument is not None.
min_bin_freq : int, default=1
To speed up the algorithm, accept only those bins with at least
min_bin_freq points as seeds.
cluster_all : bool, default=True
If true, then all points are clustered, even those orphans that are
not within any kernel. Orphans are assigned to the nearest kernel.
If false, then orphans are given cluster label -1.
n_jobs : int, default=None
The number of jobs to use for the computation. The following tasks benefit
from the parallelization:
- The search of nearest neighbors for bandwidth estimation and label
assignments. See the details in the docstring of the
``NearestNeighbors`` class.
- Hill-climbing optimization for all seeds.
See :term:`Glossary <n_jobs>` for more details.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
max_iter : int, default=300
Maximum number of iterations, per seed point before the clustering
operation terminates (for that seed point), if has not converged yet.
.. versionadded:: 0.22
Attributes
----------
cluster_centers_ : ndarray of shape (n_clusters, n_features)
Coordinates of cluster centers.
labels_ : ndarray of shape (n_samples,)
Labels of each point.
n_iter_ : int
Maximum number of iterations performed on each seed.
.. versionadded:: 0.22
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
KMeans : K-Means clustering.
Notes
-----
Scalability:
Because this implementation uses a flat kernel and
a Ball Tree to look up members of each kernel, the complexity will tend
towards O(T*n*log(n)) in lower dimensions, with n the number of samples
and T the number of points. In higher dimensions the complexity will
tend towards O(T*n^2).
Scalability can be boosted by using fewer seeds, for example by using
a higher value of min_bin_freq in the get_bin_seeds function.
Note that the estimate_bandwidth function is much less scalable than the
mean shift algorithm and will be the bottleneck if it is used.
References
----------
Dorin Comaniciu and Peter Meer, "Mean Shift: A robust approach toward
feature space analysis". IEEE Transactions on Pattern Analysis and
Machine Intelligence. 2002. pp. 603-619.
Examples
--------
>>> from sklearn.cluster import MeanShift
>>> import numpy as np
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> clustering = MeanShift(bandwidth=2).fit(X)
>>> clustering.labels_
array([1, 1, 1, 0, 0, 0])
>>> clustering.predict([[0, 0], [5, 5]])
array([1, 0])
>>> clustering
MeanShift(bandwidth=2)
For a comparison of Mean Shift clustering with other clustering algorithms, see
:ref:`sphx_glr_auto_examples_cluster_plot_cluster_comparison.py`
"""
_parameter_constraints: dict = {
"bandwidth": [Interval(Real, 0, None, closed="neither"), None],
"seeds": ["array-like", None],
"bin_seeding": ["boolean"],
"min_bin_freq": [Interval(Integral, 1, None, closed="left")],
"cluster_all": ["boolean"],
"n_jobs": [Integral, None],
"max_iter": [Interval(Integral, 0, None, closed="left")],
}
def __init__(
self,
*,
bandwidth=None,
seeds=None,
bin_seeding=False,
min_bin_freq=1,
cluster_all=True,
n_jobs=None,
max_iter=300,
):
self.bandwidth = bandwidth
self.seeds = seeds
self.bin_seeding = bin_seeding
self.cluster_all = cluster_all
self.min_bin_freq = min_bin_freq
self.n_jobs = n_jobs
self.max_iter = max_iter
@_fit_context(prefer_skip_nested_validation=True)
def fit(self, X, y=None):
"""Perform clustering.
Parameters
----------
X : array-like of shape (n_samples, n_features)
Samples to cluster.
y : Ignored
Not used, present for API consistency by convention.
Returns
-------
self : object
Fitted instance.
"""
X = validate_data(self, X)
bandwidth = self.bandwidth
if bandwidth is None:
bandwidth = estimate_bandwidth(X, n_jobs=self.n_jobs)
seeds = self.seeds
if seeds is None:
if self.bin_seeding:
seeds = get_bin_seeds(X, bandwidth, self.min_bin_freq)
else:
seeds = X
n_samples, n_features = X.shape
center_intensity_dict = {}
# We use n_jobs=1 because this will be used in nested calls under
# parallel calls to _mean_shift_single_seed so there is no need for
# for further parallelism.
nbrs = NearestNeighbors(radius=bandwidth, n_jobs=1).fit(X)
# execute iterations on all seeds in parallel
all_res = Parallel(n_jobs=self.n_jobs)(
delayed(_mean_shift_single_seed)(seed, X, nbrs, self.max_iter)
for seed in seeds
)
# copy results in a dictionary
for i in range(len(seeds)):
if all_res[i][1]: # i.e. len(points_within) > 0
center_intensity_dict[all_res[i][0]] = all_res[i][1]
self.n_iter_ = max([x[2] for x in all_res])
if not center_intensity_dict:
# nothing near seeds
raise ValueError(
"No point was within bandwidth=%f of any seed. Try a different seeding"
" strategy or increase the bandwidth."
% bandwidth
)
# POST PROCESSING: remove near duplicate points
# If the distance between two kernels is less than the bandwidth,
# then we have to remove one because it is a duplicate. Remove the
# one with fewer points.
sorted_by_intensity = sorted(
center_intensity_dict.items(),
key=lambda tup: (tup[1], tup[0]),
reverse=True,
)
sorted_centers = np.array([tup[0] for tup in sorted_by_intensity])
unique = np.ones(len(sorted_centers), dtype=bool)
nbrs = NearestNeighbors(radius=bandwidth, n_jobs=self.n_jobs).fit(
sorted_centers
)
for i, center in enumerate(sorted_centers):
if unique[i]:
neighbor_idxs = nbrs.radius_neighbors([center], return_distance=False)[
0
]
unique[neighbor_idxs] = 0
unique[i] = 1 # leave the current point as unique
cluster_centers = sorted_centers[unique]
# ASSIGN LABELS: a point belongs to the cluster that it is closest to
nbrs = NearestNeighbors(n_neighbors=1, n_jobs=self.n_jobs).fit(cluster_centers)
labels = np.zeros(n_samples, dtype=int)
distances, idxs = nbrs.kneighbors(X)
if self.cluster_all:
labels = idxs.flatten()
else:
labels.fill(-1)
bool_selector = distances.flatten() <= bandwidth
labels[bool_selector] = idxs.flatten()[bool_selector]
self.cluster_centers_, self.labels_ = cluster_centers, labels
return self
def predict(self, X):
"""Predict the closest cluster each sample in X belongs to.
Parameters
----------
X : array-like of shape (n_samples, n_features)
New data to predict.
Returns
-------
labels : ndarray of shape (n_samples,)
Index of the cluster each sample belongs to.
"""
check_is_fitted(self)
X = validate_data(self, X, reset=False)
with config_context(assume_finite=True):
return pairwise_distances_argmin(X, self.cluster_centers_)

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"""Algorithms for spectral clustering"""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
from numbers import Integral, Real
import numpy as np
from scipy.linalg import LinAlgError, qr, svd
from scipy.sparse import csc_matrix
from sklearn.base import BaseEstimator, ClusterMixin, _fit_context
from sklearn.cluster._kmeans import k_means
from sklearn.manifold._spectral_embedding import _spectral_embedding
from sklearn.metrics.pairwise import KERNEL_PARAMS, pairwise_kernels
from sklearn.neighbors import NearestNeighbors, kneighbors_graph
from sklearn.utils import as_float_array, check_random_state
from sklearn.utils._param_validation import Interval, StrOptions, validate_params
from sklearn.utils.validation import validate_data
def cluster_qr(vectors):
"""Find the discrete partition closest to the eigenvector embedding.
This implementation was proposed in [1]_.
.. versionadded:: 1.1
Parameters
----------
vectors : array-like, shape: (n_samples, n_clusters)
The embedding space of the samples.
Returns
-------
labels : array of integers, shape: n_samples
The cluster labels of vectors.
References
----------
.. [1] :doi:`Simple, direct, and efficient multi-way spectral clustering, 2019
Anil Damle, Victor Minden, Lexing Ying
<10.1093/imaiai/iay008>`
"""
k = vectors.shape[1]
_, _, piv = qr(vectors.T, pivoting=True)
ut, _, v = svd(vectors[piv[:k], :].T)
vectors = abs(np.dot(vectors, np.dot(ut, v.conj())))
return vectors.argmax(axis=1)
def discretize(
vectors, *, copy=True, max_svd_restarts=30, n_iter_max=20, random_state=None
):
"""Search for a partition matrix which is closest to the eigenvector embedding.
This implementation was proposed in [1]_.
Parameters
----------
vectors : array-like of shape (n_samples, n_clusters)
The embedding space of the samples.
copy : bool, default=True
Whether to copy vectors, or perform in-place normalization.
max_svd_restarts : int, default=30
Maximum number of attempts to restart SVD if convergence fails
n_iter_max : int, default=30
Maximum number of iterations to attempt in rotation and partition
matrix search if machine precision convergence is not reached
random_state : int, RandomState instance, default=None
Determines random number generation for rotation matrix initialization.
Use an int to make the randomness deterministic.
See :term:`Glossary <random_state>`.
Returns
-------
labels : array of integers, shape: n_samples
The labels of the clusters.
References
----------
.. [1] `Multiclass spectral clustering, 2003
Stella X. Yu, Jianbo Shi
<https://people.eecs.berkeley.edu/~jordan/courses/281B-spring04/readings/yu-shi.pdf>`_
Notes
-----
The eigenvector embedding is used to iteratively search for the
closest discrete partition. First, the eigenvector embedding is
normalized to the space of partition matrices. An optimal discrete
partition matrix closest to this normalized embedding multiplied by
an initial rotation is calculated. Fixing this discrete partition
matrix, an optimal rotation matrix is calculated. These two
calculations are performed until convergence. The discrete partition
matrix is returned as the clustering solution. Used in spectral
clustering, this method tends to be faster and more robust to random
initialization than k-means.
"""
random_state = check_random_state(random_state)
vectors = as_float_array(vectors, copy=copy)
eps = np.finfo(float).eps
n_samples, n_components = vectors.shape
# Normalize the eigenvectors to an equal length of a vector of ones.
# Reorient the eigenvectors to point in the negative direction with respect
# to the first element. This may have to do with constraining the
# eigenvectors to lie in a specific quadrant to make the discretization
# search easier.
norm_ones = np.sqrt(n_samples)
for i in range(vectors.shape[1]):
vectors[:, i] = (vectors[:, i] / np.linalg.norm(vectors[:, i])) * norm_ones
if vectors[0, i] != 0:
vectors[:, i] = -1 * vectors[:, i] * np.sign(vectors[0, i])
# Normalize the rows of the eigenvectors. Samples should lie on the unit
# hypersphere centered at the origin. This transforms the samples in the
# embedding space to the space of partition matrices.
vectors = vectors / np.sqrt((vectors**2).sum(axis=1))[:, np.newaxis]
svd_restarts = 0
has_converged = False
# If there is an exception we try to randomize and rerun SVD again
# do this max_svd_restarts times.
while (svd_restarts < max_svd_restarts) and not has_converged:
# Initialize first column of rotation matrix with a row of the
# eigenvectors
rotation = np.zeros((n_components, n_components))
rotation[:, 0] = vectors[random_state.randint(n_samples), :].T
# To initialize the rest of the rotation matrix, find the rows
# of the eigenvectors that are as orthogonal to each other as
# possible
c = np.zeros(n_samples)
for j in range(1, n_components):
# Accumulate c to ensure row is as orthogonal as possible to
# previous picks as well as current one
c += np.abs(np.dot(vectors, rotation[:, j - 1]))
rotation[:, j] = vectors[c.argmin(), :].T
last_objective_value = 0.0
n_iter = 0
while not has_converged:
n_iter += 1
t_discrete = np.dot(vectors, rotation)
labels = t_discrete.argmax(axis=1)
vectors_discrete = csc_matrix(
(np.ones(len(labels)), (np.arange(0, n_samples), labels)),
shape=(n_samples, n_components),
)
t_svd = vectors_discrete.T @ vectors
try:
U, S, Vh = np.linalg.svd(t_svd)
except LinAlgError:
svd_restarts += 1
print("SVD did not converge, randomizing and trying again")
break
ncut_value = 2.0 * (n_samples - S.sum())
if (abs(ncut_value - last_objective_value) < eps) or (n_iter > n_iter_max):
has_converged = True
else:
# otherwise calculate rotation and continue
last_objective_value = ncut_value
rotation = np.dot(Vh.T, U.T)
if not has_converged:
raise LinAlgError("SVD did not converge")
return labels
@validate_params(
{"affinity": ["array-like", "sparse matrix"]},
prefer_skip_nested_validation=False,
)
def spectral_clustering(
affinity,
*,
n_clusters=8,
n_components=None,
eigen_solver=None,
random_state=None,
n_init=10,
eigen_tol="auto",
assign_labels="kmeans",
verbose=False,
):
"""Apply clustering to a projection of the normalized Laplacian.
In practice Spectral Clustering is very useful when the structure of
the individual clusters is highly non-convex or more generally when
a measure of the center and spread of the cluster is not a suitable
description of the complete cluster. For instance, when clusters are
nested circles on the 2D plane.
If affinity is the adjacency matrix of a graph, this method can be
used to find normalized graph cuts [1]_, [2]_.
Read more in the :ref:`User Guide <spectral_clustering>`.
Parameters
----------
affinity : {array-like, sparse matrix} of shape (n_samples, n_samples)
The affinity matrix describing the relationship of the samples to
embed. **Must be symmetric**.
Possible examples:
- adjacency matrix of a graph,
- heat kernel of the pairwise distance matrix of the samples,
- symmetric k-nearest neighbours connectivity matrix of the samples.
n_clusters : int, default=None
Number of clusters to extract.
n_components : int, default=n_clusters
Number of eigenvectors to use for the spectral embedding.
eigen_solver : {None, 'arpack', 'lobpcg', or 'amg'}
The eigenvalue decomposition method. If None then ``'arpack'`` is used.
See [4]_ for more details regarding ``'lobpcg'``.
Eigensolver ``'amg'`` runs ``'lobpcg'`` with optional
Algebraic MultiGrid preconditioning and requires pyamg to be installed.
It can be faster on very large sparse problems [6]_ and [7]_.
random_state : int, RandomState instance, default=None
A pseudo random number generator used for the initialization
of the lobpcg eigenvectors decomposition when `eigen_solver ==
'amg'`, and for the K-Means initialization. Use an int to make
the results deterministic across calls (See
:term:`Glossary <random_state>`).
.. note::
When using `eigen_solver == 'amg'`,
it is necessary to also fix the global numpy seed with
`np.random.seed(int)` to get deterministic results. See
https://github.com/pyamg/pyamg/issues/139 for further
information.
n_init : int, default=10
Number of time the k-means algorithm will be run with different
centroid seeds. The final results will be the best output of n_init
consecutive runs in terms of inertia. Only used if
``assign_labels='kmeans'``.
eigen_tol : float, default="auto"
Stopping criterion for eigendecomposition of the Laplacian matrix.
If `eigen_tol="auto"` then the passed tolerance will depend on the
`eigen_solver`:
- If `eigen_solver="arpack"`, then `eigen_tol=0.0`;
- If `eigen_solver="lobpcg"` or `eigen_solver="amg"`, then
`eigen_tol=None` which configures the underlying `lobpcg` solver to
automatically resolve the value according to their heuristics. See,
:func:`scipy.sparse.linalg.lobpcg` for details.
Note that when using `eigen_solver="lobpcg"` or `eigen_solver="amg"`
values of `tol<1e-5` may lead to convergence issues and should be
avoided.
.. versionadded:: 1.2
Added 'auto' option.
assign_labels : {'kmeans', 'discretize', 'cluster_qr'}, default='kmeans'
The strategy to use to assign labels in the embedding
space. There are three ways to assign labels after the Laplacian
embedding. k-means can be applied and is a popular choice. But it can
also be sensitive to initialization. Discretization is another
approach which is less sensitive to random initialization [3]_.
The cluster_qr method [5]_ directly extracts clusters from eigenvectors
in spectral clustering. In contrast to k-means and discretization, cluster_qr
has no tuning parameters and is not an iterative method, yet may outperform
k-means and discretization in terms of both quality and speed. For a detailed
comparison of clustering strategies, refer to the following example:
:ref:`sphx_glr_auto_examples_cluster_plot_coin_segmentation.py`.
.. versionchanged:: 1.1
Added new labeling method 'cluster_qr'.
verbose : bool, default=False
Verbosity mode.
.. versionadded:: 0.24
Returns
-------
labels : array of integers, shape: n_samples
The labels of the clusters.
Notes
-----
The graph should contain only one connected component, elsewhere
the results make little sense.
This algorithm solves the normalized cut for `k=2`: it is a
normalized spectral clustering.
References
----------
.. [1] :doi:`Normalized cuts and image segmentation, 2000
Jianbo Shi, Jitendra Malik
<10.1109/34.868688>`
.. [2] :doi:`A Tutorial on Spectral Clustering, 2007
Ulrike von Luxburg
<10.1007/s11222-007-9033-z>`
.. [3] `Multiclass spectral clustering, 2003
Stella X. Yu, Jianbo Shi
<https://people.eecs.berkeley.edu/~jordan/courses/281B-spring04/readings/yu-shi.pdf>`_
.. [4] :doi:`Toward the Optimal Preconditioned Eigensolver:
Locally Optimal Block Preconditioned Conjugate Gradient Method, 2001
A. V. Knyazev
SIAM Journal on Scientific Computing 23, no. 2, pp. 517-541.
<10.1137/S1064827500366124>`
.. [5] :doi:`Simple, direct, and efficient multi-way spectral clustering, 2019
Anil Damle, Victor Minden, Lexing Ying
<10.1093/imaiai/iay008>`
.. [6] :doi:`Multiscale Spectral Image Segmentation Multiscale preconditioning
for computing eigenvalues of graph Laplacians in image segmentation, 2006
Andrew Knyazev
<10.13140/RG.2.2.35280.02565>`
.. [7] :doi:`Preconditioned spectral clustering for stochastic block partition
streaming graph challenge (Preliminary version at arXiv.)
David Zhuzhunashvili, Andrew Knyazev
<10.1109/HPEC.2017.8091045>`
Examples
--------
>>> import numpy as np
>>> from sklearn.metrics.pairwise import pairwise_kernels
>>> from sklearn.cluster import spectral_clustering
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> affinity = pairwise_kernels(X, metric='rbf')
>>> spectral_clustering(
... affinity=affinity, n_clusters=2, assign_labels="discretize", random_state=0
... )
array([1, 1, 1, 0, 0, 0])
"""
clusterer = SpectralClustering(
n_clusters=n_clusters,
n_components=n_components,
eigen_solver=eigen_solver,
random_state=random_state,
n_init=n_init,
affinity="precomputed",
eigen_tol=eigen_tol,
assign_labels=assign_labels,
verbose=verbose,
).fit(affinity)
return clusterer.labels_
class SpectralClustering(ClusterMixin, BaseEstimator):
"""Apply clustering to a projection of the normalized Laplacian.
In practice Spectral Clustering is very useful when the structure of
the individual clusters is highly non-convex, or more generally when
a measure of the center and spread of the cluster is not a suitable
description of the complete cluster, such as when clusters are
nested circles on the 2D plane.
If the affinity matrix is the adjacency matrix of a graph, this method
can be used to find normalized graph cuts [1]_, [2]_.
When calling ``fit``, an affinity matrix is constructed using either
a kernel function such the Gaussian (aka RBF) kernel with Euclidean
distance ``d(X, X)``::
np.exp(-gamma * d(X,X) ** 2)
or a k-nearest neighbors connectivity matrix.
Alternatively, a user-provided affinity matrix can be specified by
setting ``affinity='precomputed'``.
Read more in the :ref:`User Guide <spectral_clustering>`.
Parameters
----------
n_clusters : int, default=8
The dimension of the projection subspace.
eigen_solver : {'arpack', 'lobpcg', 'amg'}, default=None
The eigenvalue decomposition strategy to use. AMG requires pyamg
to be installed. It can be faster on very large, sparse problems,
but may also lead to instabilities. If None, then ``'arpack'`` is
used. See [4]_ for more details regarding `'lobpcg'`.
n_components : int, default=None
Number of eigenvectors to use for the spectral embedding. If None,
defaults to `n_clusters`.
random_state : int, RandomState instance, default=None
A pseudo random number generator used for the initialization
of the lobpcg eigenvectors decomposition when `eigen_solver ==
'amg'`, and for the K-Means initialization. Use an int to make
the results deterministic across calls (See
:term:`Glossary <random_state>`).
.. note::
When using `eigen_solver == 'amg'`,
it is necessary to also fix the global numpy seed with
`np.random.seed(int)` to get deterministic results. See
https://github.com/pyamg/pyamg/issues/139 for further
information.
n_init : int, default=10
Number of time the k-means algorithm will be run with different
centroid seeds. The final results will be the best output of n_init
consecutive runs in terms of inertia. Only used if
``assign_labels='kmeans'``.
gamma : float, default=1.0
Kernel coefficient for rbf, poly, sigmoid, laplacian and chi2 kernels.
Ignored for ``affinity='nearest_neighbors'``, ``affinity='precomputed'``
or ``affinity='precomputed_nearest_neighbors'``.
affinity : str or callable, default='rbf'
How to construct the affinity matrix.
- 'nearest_neighbors': construct the affinity matrix by computing a
graph of nearest neighbors.
- 'rbf': construct the affinity matrix using a radial basis function
(RBF) kernel.
- 'precomputed': interpret ``X`` as a precomputed affinity matrix,
where larger values indicate greater similarity between instances.
- 'precomputed_nearest_neighbors': interpret ``X`` as a sparse graph
of precomputed distances, and construct a binary affinity matrix
from the ``n_neighbors`` nearest neighbors of each instance.
- one of the kernels supported by
:func:`~sklearn.metrics.pairwise.pairwise_kernels`.
Only kernels that produce similarity scores (non-negative values that
increase with similarity) should be used. This property is not checked
by the clustering algorithm.
n_neighbors : int, default=10
Number of neighbors to use when constructing the affinity matrix using
the nearest neighbors method. Ignored for ``affinity='rbf'``.
eigen_tol : float, default="auto"
Stopping criterion for eigen decomposition of the Laplacian matrix.
If `eigen_tol="auto"` then the passed tolerance will depend on the
`eigen_solver`:
- If `eigen_solver="arpack"`, then `eigen_tol=0.0`;
- If `eigen_solver="lobpcg"` or `eigen_solver="amg"`, then
`eigen_tol=None` which configures the underlying `lobpcg` solver to
automatically resolve the value according to their heuristics. See,
:func:`scipy.sparse.linalg.lobpcg` for details.
Note that when using `eigen_solver="lobpcg"` or `eigen_solver="amg"`
values of `tol<1e-5` may lead to convergence issues and should be
avoided.
.. versionadded:: 1.2
Added 'auto' option.
assign_labels : {'kmeans', 'discretize', 'cluster_qr'}, default='kmeans'
The strategy for assigning labels in the embedding space. There are two
ways to assign labels after the Laplacian embedding. k-means is a
popular choice, but it can be sensitive to initialization.
Discretization is another approach which is less sensitive to random
initialization [3]_.
The cluster_qr method [5]_ directly extract clusters from eigenvectors
in spectral clustering. In contrast to k-means and discretization, cluster_qr
has no tuning parameters and runs no iterations, yet may outperform
k-means and discretization in terms of both quality and speed.
.. versionchanged:: 1.1
Added new labeling method 'cluster_qr'.
degree : float, default=3
Degree of the polynomial kernel. Ignored by other kernels.
coef0 : float, default=1
Zero coefficient for polynomial and sigmoid kernels.
Ignored by other kernels.
kernel_params : dict of str to any, default=None
Parameters (keyword arguments) and values for kernel passed as
callable object. Ignored by other kernels.
n_jobs : int, default=None
The number of parallel jobs to run when `affinity='nearest_neighbors'`
or `affinity='precomputed_nearest_neighbors'`. The neighbors search
will be done in parallel.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
verbose : bool, default=False
Verbosity mode.
.. versionadded:: 0.24
Attributes
----------
affinity_matrix_ : array-like of shape (n_samples, n_samples)
Affinity matrix used for clustering. Available only after calling
``fit``.
labels_ : ndarray of shape (n_samples,)
Labels of each point
n_features_in_ : int
Number of features seen during :term:`fit`.
.. versionadded:: 0.24
feature_names_in_ : ndarray of shape (`n_features_in_`,)
Names of features seen during :term:`fit`. Defined only when `X`
has feature names that are all strings.
.. versionadded:: 1.0
See Also
--------
sklearn.cluster.KMeans : K-Means clustering.
sklearn.cluster.DBSCAN : Density-Based Spatial Clustering of
Applications with Noise.
Notes
-----
A distance matrix for which 0 indicates identical elements and high values
indicate very dissimilar elements can be transformed into an affinity /
similarity matrix that is well-suited for the algorithm by
applying the Gaussian (aka RBF, heat) kernel::
np.exp(- dist_matrix ** 2 / (2. * delta ** 2))
where ``delta`` is a free parameter representing the width of the Gaussian
kernel.
An alternative is to take a symmetric version of the k-nearest neighbors
connectivity matrix of the points.
If the pyamg package is installed, it is used: this greatly
speeds up computation.
References
----------
.. [1] :doi:`Normalized cuts and image segmentation, 2000
Jianbo Shi, Jitendra Malik
<10.1109/34.868688>`
.. [2] :doi:`A Tutorial on Spectral Clustering, 2007
Ulrike von Luxburg
<10.1007/s11222-007-9033-z>`
.. [3] `Multiclass spectral clustering, 2003
Stella X. Yu, Jianbo Shi
<https://people.eecs.berkeley.edu/~jordan/courses/281B-spring04/readings/yu-shi.pdf>`_
.. [4] :doi:`Toward the Optimal Preconditioned Eigensolver:
Locally Optimal Block Preconditioned Conjugate Gradient Method, 2001
A. V. Knyazev
SIAM Journal on Scientific Computing 23, no. 2, pp. 517-541.
<10.1137/S1064827500366124>`
.. [5] :doi:`Simple, direct, and efficient multi-way spectral clustering, 2019
Anil Damle, Victor Minden, Lexing Ying
<10.1093/imaiai/iay008>`
Examples
--------
>>> from sklearn.cluster import SpectralClustering
>>> import numpy as np
>>> X = np.array([[1, 1], [2, 1], [1, 0],
... [4, 7], [3, 5], [3, 6]])
>>> clustering = SpectralClustering(n_clusters=2,
... assign_labels='discretize',
... random_state=0).fit(X)
>>> clustering.labels_
array([1, 1, 1, 0, 0, 0])
>>> clustering
SpectralClustering(assign_labels='discretize', n_clusters=2,
random_state=0)
For a comparison of Spectral clustering with other clustering algorithms, see
:ref:`sphx_glr_auto_examples_cluster_plot_cluster_comparison.py`
"""
_parameter_constraints: dict = {
"n_clusters": [Interval(Integral, 1, None, closed="left")],
"eigen_solver": [StrOptions({"arpack", "lobpcg", "amg"}), None],
"n_components": [Interval(Integral, 1, None, closed="left"), None],
"random_state": ["random_state"],
"n_init": [Interval(Integral, 1, None, closed="left")],
"gamma": [Interval(Real, 0, None, closed="left")],
"affinity": [
callable,
StrOptions(
set(KERNEL_PARAMS)
| {"nearest_neighbors", "precomputed", "precomputed_nearest_neighbors"}
),
],
"n_neighbors": [Interval(Integral, 1, None, closed="left")],
"eigen_tol": [
Interval(Real, 0.0, None, closed="left"),
StrOptions({"auto"}),
],
"assign_labels": [StrOptions({"kmeans", "discretize", "cluster_qr"})],
"degree": [Interval(Real, 0, None, closed="left")],
"coef0": [Interval(Real, None, None, closed="neither")],
"kernel_params": [dict, None],
"n_jobs": [Integral, None],
"verbose": ["verbose"],
}
def __init__(
self,
n_clusters=8,
*,
eigen_solver=None,
n_components=None,
random_state=None,
n_init=10,
gamma=1.0,
affinity="rbf",
n_neighbors=10,
eigen_tol="auto",
assign_labels="kmeans",
degree=3,
coef0=1,
kernel_params=None,
n_jobs=None,
verbose=False,
):
self.n_clusters = n_clusters
self.eigen_solver = eigen_solver
self.n_components = n_components
self.random_state = random_state
self.n_init = n_init
self.gamma = gamma
self.affinity = affinity
self.n_neighbors = n_neighbors
self.eigen_tol = eigen_tol
self.assign_labels = assign_labels
self.degree = degree
self.coef0 = coef0
self.kernel_params = kernel_params
self.n_jobs = n_jobs
self.verbose = verbose
@_fit_context(prefer_skip_nested_validation=True)
def fit(self, X, y=None):
"""Perform spectral clustering from features, or affinity matrix.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features) or \
(n_samples, n_samples)
Training instances to cluster, similarities / affinities between
instances if ``affinity='precomputed'``, or distances between
instances if ``affinity='precomputed_nearest_neighbors``. If a
sparse matrix is provided in a format other than ``csr_matrix``,
``csc_matrix``, or ``coo_matrix``, it will be converted into a
sparse ``csr_matrix``.
y : Ignored
Not used, present here for API consistency by convention.
Returns
-------
self : object
A fitted instance of the estimator.
"""
X = validate_data(
self,
X,
accept_sparse=["csr", "csc", "coo"],
dtype=np.float64,
ensure_min_samples=2,
)
allow_squared = self.affinity in [
"precomputed",
"precomputed_nearest_neighbors",
]
if X.shape[0] == X.shape[1] and not allow_squared:
warnings.warn(
"The spectral clustering API has changed. ``fit``"
"now constructs an affinity matrix from data. To use"
" a custom affinity matrix, "
"set ``affinity=precomputed``."
)
if self.affinity == "nearest_neighbors":
connectivity = kneighbors_graph(
X, n_neighbors=self.n_neighbors, include_self=True, n_jobs=self.n_jobs
)
self.affinity_matrix_ = 0.5 * (connectivity + connectivity.T)
elif self.affinity == "precomputed_nearest_neighbors":
estimator = NearestNeighbors(
n_neighbors=self.n_neighbors, n_jobs=self.n_jobs, metric="precomputed"
).fit(X)
connectivity = estimator.kneighbors_graph(X=X, mode="connectivity")
self.affinity_matrix_ = 0.5 * (connectivity + connectivity.T)
elif self.affinity == "precomputed":
self.affinity_matrix_ = X
else:
params = self.kernel_params
if params is None:
params = {}
if not callable(self.affinity):
params["gamma"] = self.gamma
params["degree"] = self.degree
params["coef0"] = self.coef0
self.affinity_matrix_ = pairwise_kernels(
X, metric=self.affinity, filter_params=True, **params
)
random_state = check_random_state(self.random_state)
n_components = (
self.n_clusters if self.n_components is None else self.n_components
)
# We now obtain the real valued solution matrix to the
# relaxed Ncut problem, solving the eigenvalue problem
# L_sym x = lambda x and recovering u = D^-1/2 x.
# The first eigenvector is constant only for fully connected graphs
# and should be kept for spectral clustering (drop_first = False)
# See spectral_embedding documentation.
maps = _spectral_embedding(
self.affinity_matrix_,
n_components=n_components,
eigen_solver=self.eigen_solver,
random_state=random_state,
eigen_tol=self.eigen_tol,
drop_first=False,
)
if self.verbose:
print(f"Computing label assignment using {self.assign_labels}")
if self.assign_labels == "kmeans":
_, self.labels_, _ = k_means(
maps,
self.n_clusters,
random_state=random_state,
n_init=self.n_init,
verbose=self.verbose,
)
elif self.assign_labels == "cluster_qr":
self.labels_ = cluster_qr(maps)
else:
self.labels_ = discretize(maps, random_state=random_state)
return self
def fit_predict(self, X, y=None):
"""Perform spectral clustering on `X` and return cluster labels.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features) or \
(n_samples, n_samples)
Training instances to cluster, similarities / affinities between
instances if ``affinity='precomputed'``, or distances between
instances if ``affinity='precomputed_nearest_neighbors``. If a
sparse matrix is provided in a format other than ``csr_matrix``,
``csc_matrix``, or ``coo_matrix``, it will be converted into a
sparse ``csr_matrix``.
y : Ignored
Not used, present here for API consistency by convention.
Returns
-------
labels : ndarray of shape (n_samples,)
Cluster labels.
"""
return super().fit_predict(X, y)
def __sklearn_tags__(self):
tags = super().__sklearn_tags__()
tags.input_tags.sparse = True
tags.input_tags.pairwise = self.affinity in [
"precomputed",
"precomputed_nearest_neighbors",
]
return tags

View File

@@ -0,0 +1,26 @@
cluster_extension_metadata = {
'_dbscan_inner':
{'sources': [cython_gen_cpp.process('_dbscan_inner.pyx')]},
'_hierarchical_fast':
{'sources': [cython_gen_cpp.process('_hierarchical_fast.pyx'), metrics_cython_tree]},
'_k_means_common':
{'sources': [cython_gen.process('_k_means_common.pyx')], 'dependencies': [openmp_dep]},
'_k_means_lloyd':
{'sources': [cython_gen.process('_k_means_lloyd.pyx')], 'dependencies': [openmp_dep]},
'_k_means_elkan':
{'sources': [cython_gen.process('_k_means_elkan.pyx')], 'dependencies': [openmp_dep]},
'_k_means_minibatch':
{'sources': [cython_gen.process('_k_means_minibatch.pyx')], 'dependencies': [openmp_dep]},
}
foreach ext_name, ext_dict : cluster_extension_metadata
py.extension_module(
ext_name,
[ext_dict.get('sources'), utils_cython_tree],
dependencies: [np_dep] + ext_dict.get('dependencies', []),
subdir: 'sklearn/cluster',
install: true
)
endforeach
subdir('_hdbscan')

View File

@@ -0,0 +1,37 @@
"""
Common utilities for testing clustering.
"""
import numpy as np
###############################################################################
# Generate sample data
def generate_clustered_data(
seed=0, n_clusters=3, n_features=2, n_samples_per_cluster=20, std=0.4
):
prng = np.random.RandomState(seed)
# the data is voluntary shifted away from zero to check clustering
# algorithm robustness with regards to non centered data
means = (
np.array(
[
[1, 1, 1, 0],
[-1, -1, 0, 1],
[1, -1, 1, 1],
[-1, 1, 1, 0],
]
)
+ 10
)
X = np.empty((0, n_features))
for i in range(n_clusters):
X = np.r_[
X,
means[i][:n_features] + std * prng.randn(n_samples_per_cluster, n_features),
]
return X

View File

@@ -0,0 +1,321 @@
"""
Testing for Clustering methods
"""
import warnings
import numpy as np
import pytest
from sklearn.cluster import AffinityPropagation, affinity_propagation
from sklearn.cluster._affinity_propagation import _equal_similarities_and_preferences
from sklearn.datasets import make_blobs
from sklearn.exceptions import ConvergenceWarning, NotFittedError
from sklearn.metrics import euclidean_distances
from sklearn.utils._testing import assert_allclose, assert_array_equal
from sklearn.utils.fixes import CSR_CONTAINERS
n_clusters = 3
centers = np.array([[1, 1], [-1, -1], [1, -1]]) + 10
X, _ = make_blobs(
n_samples=60,
n_features=2,
centers=centers,
cluster_std=0.4,
shuffle=True,
random_state=0,
)
# TODO: AffinityPropagation must preserve dtype for its fitted attributes
# and test must be created accordingly to this new behavior.
# For more details, see: https://github.com/scikit-learn/scikit-learn/issues/11000
def test_affinity_propagation(global_random_seed, global_dtype):
"""Test consistency of the affinity propagations."""
S = -euclidean_distances(X.astype(global_dtype, copy=False), squared=True)
preference = np.median(S) * 10
cluster_centers_indices, labels = affinity_propagation(
S, preference=preference, random_state=global_random_seed
)
n_clusters_ = len(cluster_centers_indices)
assert n_clusters == n_clusters_
def test_affinity_propagation_precomputed():
"""Check equality of precomputed affinity matrix to internally computed affinity
matrix.
"""
S = -euclidean_distances(X, squared=True)
preference = np.median(S) * 10
af = AffinityPropagation(
preference=preference, affinity="precomputed", random_state=28
)
labels_precomputed = af.fit(S).labels_
af = AffinityPropagation(preference=preference, verbose=True, random_state=37)
labels = af.fit(X).labels_
assert_array_equal(labels, labels_precomputed)
cluster_centers_indices = af.cluster_centers_indices_
n_clusters_ = len(cluster_centers_indices)
assert np.unique(labels).size == n_clusters_
assert n_clusters == n_clusters_
def test_affinity_propagation_no_copy():
"""Check behaviour of not copying the input data."""
S = -euclidean_distances(X, squared=True)
S_original = S.copy()
preference = np.median(S) * 10
assert not np.allclose(S.diagonal(), preference)
# with copy=True S should not be modified
affinity_propagation(S, preference=preference, copy=True, random_state=0)
assert_allclose(S, S_original)
assert not np.allclose(S.diagonal(), preference)
assert_allclose(S.diagonal(), np.zeros(S.shape[0]))
# with copy=False S will be modified inplace
affinity_propagation(S, preference=preference, copy=False, random_state=0)
assert_allclose(S.diagonal(), preference)
# test that copy=True and copy=False lead to the same result
S = S_original.copy()
af = AffinityPropagation(preference=preference, verbose=True, random_state=0)
labels = af.fit(X).labels_
_, labels_no_copy = affinity_propagation(
S, preference=preference, copy=False, random_state=74
)
assert_array_equal(labels, labels_no_copy)
def test_affinity_propagation_affinity_shape():
"""Check the shape of the affinity matrix when using `affinity_propagation."""
S = -euclidean_distances(X, squared=True)
err_msg = "The matrix of similarities must be a square array"
with pytest.raises(ValueError, match=err_msg):
affinity_propagation(S[:, :-1])
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_affinity_propagation_precomputed_with_sparse_input(csr_container):
err_msg = "Sparse data was passed for X, but dense data is required"
with pytest.raises(TypeError, match=err_msg):
AffinityPropagation(affinity="precomputed").fit(csr_container((3, 3)))
def test_affinity_propagation_predict(global_random_seed, global_dtype):
# Test AffinityPropagation.predict
af = AffinityPropagation(affinity="euclidean", random_state=global_random_seed)
X_ = X.astype(global_dtype, copy=False)
labels = af.fit_predict(X_)
labels2 = af.predict(X_)
assert_array_equal(labels, labels2)
def test_affinity_propagation_predict_error():
# Test exception in AffinityPropagation.predict
# Not fitted.
af = AffinityPropagation(affinity="euclidean")
with pytest.raises(NotFittedError):
af.predict(X)
# Predict not supported when affinity="precomputed".
S = np.dot(X, X.T)
af = AffinityPropagation(affinity="precomputed", random_state=57)
af.fit(S)
with pytest.raises(ValueError, match="expecting 60 features as input"):
af.predict(X)
def test_affinity_propagation_fit_non_convergence(global_dtype):
# In case of non-convergence of affinity_propagation(), the cluster
# centers should be an empty array and training samples should be labelled
# as noise (-1)
X = np.array([[0, 0], [1, 1], [-2, -2]], dtype=global_dtype)
# Force non-convergence by allowing only a single iteration
af = AffinityPropagation(preference=-10, max_iter=1, random_state=82)
with pytest.warns(ConvergenceWarning):
af.fit(X)
assert_allclose(np.empty((0, 2)), af.cluster_centers_)
assert_array_equal(np.array([-1, -1, -1]), af.labels_)
def test_affinity_propagation_equal_mutual_similarities(global_dtype):
X = np.array([[-1, 1], [1, -1]], dtype=global_dtype)
S = -euclidean_distances(X, squared=True)
# setting preference > similarity
with pytest.warns(UserWarning, match="mutually equal"):
cluster_center_indices, labels = affinity_propagation(S, preference=0)
# expect every sample to become an exemplar
assert_array_equal([0, 1], cluster_center_indices)
assert_array_equal([0, 1], labels)
# setting preference < similarity
with pytest.warns(UserWarning, match="mutually equal"):
cluster_center_indices, labels = affinity_propagation(S, preference=-10)
# expect one cluster, with arbitrary (first) sample as exemplar
assert_array_equal([0], cluster_center_indices)
assert_array_equal([0, 0], labels)
# setting different preferences
with warnings.catch_warnings():
warnings.simplefilter("error", UserWarning)
cluster_center_indices, labels = affinity_propagation(
S, preference=[-20, -10], random_state=37
)
# expect one cluster, with highest-preference sample as exemplar
assert_array_equal([1], cluster_center_indices)
assert_array_equal([0, 0], labels)
def test_affinity_propagation_predict_non_convergence(global_dtype):
# In case of non-convergence of affinity_propagation(), the cluster
# centers should be an empty array
X = np.array([[0, 0], [1, 1], [-2, -2]], dtype=global_dtype)
# Force non-convergence by allowing only a single iteration
with pytest.warns(ConvergenceWarning):
af = AffinityPropagation(preference=-10, max_iter=1, random_state=75).fit(X)
# At prediction time, consider new samples as noise since there are no
# clusters
to_predict = np.array([[2, 2], [3, 3], [4, 4]])
with pytest.warns(ConvergenceWarning):
y = af.predict(to_predict)
assert_array_equal(np.array([-1, -1, -1]), y)
def test_affinity_propagation_non_convergence_regressiontest(global_dtype):
X = np.array(
[[1, 0, 0, 0, 0, 0], [0, 1, 1, 1, 0, 0], [0, 0, 1, 0, 0, 1]], dtype=global_dtype
)
af = AffinityPropagation(affinity="euclidean", max_iter=2, random_state=34)
msg = (
"Affinity propagation did not converge, this model may return degenerate"
" cluster centers and labels."
)
with pytest.warns(ConvergenceWarning, match=msg):
af.fit(X)
assert_array_equal(np.array([0, 0, 0]), af.labels_)
def test_equal_similarities_and_preferences(global_dtype):
# Unequal distances
X = np.array([[0, 0], [1, 1], [-2, -2]], dtype=global_dtype)
S = -euclidean_distances(X, squared=True)
assert not _equal_similarities_and_preferences(S, np.array(0))
assert not _equal_similarities_and_preferences(S, np.array([0, 0]))
assert not _equal_similarities_and_preferences(S, np.array([0, 1]))
# Equal distances
X = np.array([[0, 0], [1, 1]], dtype=global_dtype)
S = -euclidean_distances(X, squared=True)
# Different preferences
assert not _equal_similarities_and_preferences(S, np.array([0, 1]))
# Same preferences
assert _equal_similarities_and_preferences(S, np.array([0, 0]))
assert _equal_similarities_and_preferences(S, np.array(0))
def test_affinity_propagation_random_state():
"""Check that different random states lead to different initialisations
by looking at the center locations after two iterations.
"""
centers = [[1, 1], [-1, -1], [1, -1]]
X, labels_true = make_blobs(
n_samples=300, centers=centers, cluster_std=0.5, random_state=0
)
# random_state = 0
ap = AffinityPropagation(convergence_iter=1, max_iter=2, random_state=0)
ap.fit(X)
centers0 = ap.cluster_centers_
# random_state = 76
ap = AffinityPropagation(convergence_iter=1, max_iter=2, random_state=76)
ap.fit(X)
centers76 = ap.cluster_centers_
# check that the centers have not yet converged to the same solution
assert np.mean((centers0 - centers76) ** 2) > 1
@pytest.mark.parametrize("container", CSR_CONTAINERS + [np.array])
def test_affinity_propagation_convergence_warning_dense_sparse(container, global_dtype):
"""
Check that having sparse or dense `centers` format should not
influence the convergence.
Non-regression test for gh-13334.
"""
centers = container(np.zeros((1, 10)))
rng = np.random.RandomState(42)
X = rng.rand(40, 10).astype(global_dtype, copy=False)
y = (4 * rng.rand(40)).astype(int)
ap = AffinityPropagation(random_state=46)
ap.fit(X, y)
ap.cluster_centers_ = centers
with warnings.catch_warnings():
warnings.simplefilter("error", ConvergenceWarning)
assert_array_equal(ap.predict(X), np.zeros(X.shape[0], dtype=int))
# FIXME; this test is broken with different random states, needs to be revisited
def test_correct_clusters(global_dtype):
# Test to fix incorrect clusters due to dtype change
# (non-regression test for issue #10832)
X = np.array(
[[1, 0, 0, 0], [0, 1, 1, 0], [0, 1, 1, 0], [0, 0, 0, 1]], dtype=global_dtype
)
afp = AffinityPropagation(preference=1, affinity="precomputed", random_state=0).fit(
X
)
expected = np.array([0, 1, 1, 2])
assert_array_equal(afp.labels_, expected)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_sparse_input_for_predict(csr_container):
# Test to make sure sparse inputs are accepted for predict
# (non-regression test for issue #20049)
af = AffinityPropagation(affinity="euclidean", random_state=42)
af.fit(X)
labels = af.predict(csr_container((2, 2)))
assert_array_equal(labels, (2, 2))
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_sparse_input_for_fit_predict(csr_container):
# Test to make sure sparse inputs are accepted for fit_predict
# (non-regression test for issue #20049)
af = AffinityPropagation(affinity="euclidean", random_state=42)
rng = np.random.RandomState(42)
X = csr_container(rng.randint(0, 2, size=(5, 5)))
labels = af.fit_predict(X)
assert_array_equal(labels, (0, 1, 1, 2, 3))
def test_affinity_propagation_equal_points():
"""Make sure we do not assign multiple clusters to equal points.
Non-regression test for:
https://github.com/scikit-learn/scikit-learn/pull/20043
"""
X = np.zeros((8, 1))
af = AffinityPropagation(affinity="euclidean", damping=0.5, random_state=42).fit(X)
assert np.all(af.labels_ == 0)

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"""Testing for Spectral Biclustering methods"""
import numpy as np
import pytest
from scipy.sparse import issparse
from sklearn.base import BaseEstimator, BiclusterMixin, clone
from sklearn.cluster import SpectralBiclustering, SpectralCoclustering
from sklearn.cluster._bicluster import (
_bistochastic_normalize,
_log_normalize,
_scale_normalize,
)
from sklearn.datasets import make_biclusters, make_checkerboard
from sklearn.metrics import consensus_score, v_measure_score
from sklearn.model_selection import ParameterGrid
from sklearn.utils._testing import (
assert_almost_equal,
assert_array_almost_equal,
assert_array_equal,
)
from sklearn.utils.fixes import CSR_CONTAINERS
class MockBiclustering(BiclusterMixin, BaseEstimator):
# Mock object for testing get_submatrix.
def __init__(self):
pass
def get_indices(self, i):
# Overridden to reproduce old get_submatrix test.
return (
np.where([True, True, False, False, True])[0],
np.where([False, False, True, True])[0],
)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_get_submatrix(csr_container):
data = np.arange(20).reshape(5, 4)
model = MockBiclustering()
for X in (data, csr_container(data), data.tolist()):
submatrix = model.get_submatrix(0, X)
if issparse(submatrix):
submatrix = submatrix.toarray()
assert_array_equal(submatrix, [[2, 3], [6, 7], [18, 19]])
submatrix[:] = -1
if issparse(X):
X = X.toarray()
assert np.all(X != -1)
def _test_shape_indices(model):
# Test get_shape and get_indices on fitted model.
for i in range(model.n_clusters):
m, n = model.get_shape(i)
i_ind, j_ind = model.get_indices(i)
assert len(i_ind) == m
assert len(j_ind) == n
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_spectral_coclustering(global_random_seed, csr_container):
# Test Dhillon's Spectral CoClustering on a simple problem.
param_grid = {
"svd_method": ["randomized", "arpack"],
"n_svd_vecs": [None, 20],
"mini_batch": [False, True],
"init": ["k-means++"],
"n_init": [10],
}
S, rows, cols = make_biclusters(
(30, 30), 3, noise=0.1, random_state=global_random_seed
)
S -= S.min() # needs to be nonnegative before making it sparse
S = np.where(S < 1, 0, S) # threshold some values
for mat in (S, csr_container(S)):
for kwargs in ParameterGrid(param_grid):
model = SpectralCoclustering(
n_clusters=3, random_state=global_random_seed, **kwargs
)
model.fit(mat)
assert model.rows_.shape == (3, 30)
assert_array_equal(model.rows_.sum(axis=0), np.ones(30))
assert_array_equal(model.columns_.sum(axis=0), np.ones(30))
assert consensus_score(model.biclusters_, (rows, cols)) == 1
_test_shape_indices(model)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_spectral_biclustering(global_random_seed, csr_container):
# Test Kluger methods on a checkerboard dataset.
S, rows, cols = make_checkerboard(
(30, 30), 3, noise=0.5, random_state=global_random_seed
)
non_default_params = {
"method": ["scale", "log"],
"svd_method": ["arpack"],
"n_svd_vecs": [20],
"mini_batch": [True],
}
for mat in (S, csr_container(S)):
for param_name, param_values in non_default_params.items():
for param_value in param_values:
model = SpectralBiclustering(
n_clusters=3,
n_init=3,
init="k-means++",
random_state=global_random_seed,
)
model.set_params(**dict([(param_name, param_value)]))
if issparse(mat) and model.get_params().get("method") == "log":
# cannot take log of sparse matrix
with pytest.raises(ValueError):
model.fit(mat)
continue
else:
model.fit(mat)
assert model.rows_.shape == (9, 30)
assert model.columns_.shape == (9, 30)
assert_array_equal(model.rows_.sum(axis=0), np.repeat(3, 30))
assert_array_equal(model.columns_.sum(axis=0), np.repeat(3, 30))
assert consensus_score(model.biclusters_, (rows, cols)) == 1
_test_shape_indices(model)
def _do_scale_test(scaled):
"""Check that rows sum to one constant, and columns to another."""
row_sum = scaled.sum(axis=1)
col_sum = scaled.sum(axis=0)
if issparse(scaled):
row_sum = np.asarray(row_sum).squeeze()
col_sum = np.asarray(col_sum).squeeze()
assert_array_almost_equal(row_sum, np.tile(row_sum.mean(), 100), decimal=1)
assert_array_almost_equal(col_sum, np.tile(col_sum.mean(), 100), decimal=1)
def _do_bistochastic_test(scaled):
"""Check that rows and columns sum to the same constant."""
_do_scale_test(scaled)
assert_almost_equal(scaled.sum(axis=0).mean(), scaled.sum(axis=1).mean(), decimal=1)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_scale_normalize(global_random_seed, csr_container):
generator = np.random.RandomState(global_random_seed)
X = generator.rand(100, 100)
for mat in (X, csr_container(X)):
scaled, _, _ = _scale_normalize(mat)
_do_scale_test(scaled)
if issparse(mat):
assert issparse(scaled)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_bistochastic_normalize(global_random_seed, csr_container):
generator = np.random.RandomState(global_random_seed)
X = generator.rand(100, 100)
for mat in (X, csr_container(X)):
scaled = _bistochastic_normalize(mat)
_do_bistochastic_test(scaled)
if issparse(mat):
assert issparse(scaled)
def test_log_normalize(global_random_seed):
# adding any constant to a log-scaled matrix should make it
# bistochastic
generator = np.random.RandomState(global_random_seed)
mat = generator.rand(100, 100)
scaled = _log_normalize(mat) + 1
_do_bistochastic_test(scaled)
def test_fit_best_piecewise(global_random_seed):
model = SpectralBiclustering(random_state=global_random_seed)
vectors = np.array([[0, 0, 0, 1, 1, 1], [2, 2, 2, 3, 3, 3], [0, 1, 2, 3, 4, 5]])
best = model._fit_best_piecewise(vectors, n_best=2, n_clusters=2)
assert_array_equal(best, vectors[:2])
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_project_and_cluster(global_random_seed, csr_container):
model = SpectralBiclustering(random_state=global_random_seed)
data = np.array([[1, 1, 1], [1, 1, 1], [3, 6, 3], [3, 6, 3]])
vectors = np.array([[1, 0], [0, 1], [0, 0]])
for mat in (data, csr_container(data)):
labels = model._project_and_cluster(mat, vectors, n_clusters=2)
assert_almost_equal(v_measure_score(labels, [0, 0, 1, 1]), 1.0)
def test_perfect_checkerboard(global_random_seed):
# XXX Previously failed on build bot (not reproducible)
model = SpectralBiclustering(
3, svd_method="arpack", random_state=global_random_seed
)
S, rows, cols = make_checkerboard(
(30, 30), 3, noise=0, random_state=global_random_seed
)
model.fit(S)
assert consensus_score(model.biclusters_, (rows, cols)) == 1
S, rows, cols = make_checkerboard(
(40, 30), 3, noise=0, random_state=global_random_seed
)
model.fit(S)
assert consensus_score(model.biclusters_, (rows, cols)) == 1
S, rows, cols = make_checkerboard(
(30, 40), 3, noise=0, random_state=global_random_seed
)
model.fit(S)
assert consensus_score(model.biclusters_, (rows, cols)) == 1
@pytest.mark.parametrize(
"params, type_err, err_msg",
[
(
{"n_clusters": 6},
ValueError,
"n_clusters should be <= n_samples=5",
),
(
{"n_clusters": (3, 3, 3)},
ValueError,
"Incorrect parameter n_clusters",
),
(
{"n_clusters": (3, 6)},
ValueError,
"Incorrect parameter n_clusters",
),
(
{"n_components": 3, "n_best": 4},
ValueError,
"n_best=4 must be <= n_components=3",
),
],
)
def test_spectralbiclustering_parameter_validation(params, type_err, err_msg):
"""Check parameters validation in `SpectralBiClustering`"""
data = np.arange(25).reshape((5, 5))
model = SpectralBiclustering(**params)
with pytest.raises(type_err, match=err_msg):
model.fit(data)
@pytest.mark.parametrize("est", (SpectralBiclustering(), SpectralCoclustering()))
def test_n_features_in_(est):
X, _, _ = make_biclusters((3, 3), 3, random_state=0)
est = clone(est)
assert not hasattr(est, "n_features_in_")
est.fit(X)
assert est.n_features_in_ == 3

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"""
Tests for the birch clustering algorithm.
"""
import numpy as np
import pytest
from sklearn.cluster import AgglomerativeClustering, Birch
from sklearn.cluster.tests.common import generate_clustered_data
from sklearn.datasets import make_blobs
from sklearn.exceptions import ConvergenceWarning
from sklearn.metrics import pairwise_distances_argmin, v_measure_score
from sklearn.utils._testing import assert_allclose, assert_array_equal
from sklearn.utils.fixes import CSR_CONTAINERS
def test_n_samples_leaves_roots(global_random_seed, global_dtype):
# Sanity check for the number of samples in leaves and roots
X, y = make_blobs(n_samples=10, random_state=global_random_seed)
X = X.astype(global_dtype, copy=False)
brc = Birch()
brc.fit(X)
n_samples_root = sum([sc.n_samples_ for sc in brc.root_.subclusters_])
n_samples_leaves = sum(
[sc.n_samples_ for leaf in brc._get_leaves() for sc in leaf.subclusters_]
)
assert n_samples_leaves == X.shape[0]
assert n_samples_root == X.shape[0]
def test_partial_fit(global_random_seed, global_dtype):
# Test that fit is equivalent to calling partial_fit multiple times
X, y = make_blobs(n_samples=100, random_state=global_random_seed)
X = X.astype(global_dtype, copy=False)
brc = Birch(n_clusters=3)
brc.fit(X)
brc_partial = Birch(n_clusters=None)
brc_partial.partial_fit(X[:50])
brc_partial.partial_fit(X[50:])
assert_allclose(brc_partial.subcluster_centers_, brc.subcluster_centers_)
# Test that same global labels are obtained after calling partial_fit
# with None
brc_partial.set_params(n_clusters=3)
brc_partial.partial_fit(None)
assert_array_equal(brc_partial.subcluster_labels_, brc.subcluster_labels_)
def test_birch_predict(global_random_seed, global_dtype):
# Test the predict method predicts the nearest centroid.
rng = np.random.RandomState(global_random_seed)
X = generate_clustered_data(n_clusters=3, n_features=3, n_samples_per_cluster=10)
X = X.astype(global_dtype, copy=False)
# n_samples * n_samples_per_cluster
shuffle_indices = np.arange(30)
rng.shuffle(shuffle_indices)
X_shuffle = X[shuffle_indices, :]
brc = Birch(n_clusters=4, threshold=1.0)
brc.fit(X_shuffle)
# Birch must preserve inputs' dtype
assert brc.subcluster_centers_.dtype == global_dtype
assert_array_equal(brc.labels_, brc.predict(X_shuffle))
centroids = brc.subcluster_centers_
nearest_centroid = brc.subcluster_labels_[
pairwise_distances_argmin(X_shuffle, centroids)
]
assert_allclose(v_measure_score(nearest_centroid, brc.labels_), 1.0)
def test_n_clusters(global_random_seed, global_dtype):
# Test that n_clusters param works properly
X, y = make_blobs(n_samples=100, centers=10, random_state=global_random_seed)
X = X.astype(global_dtype, copy=False)
brc1 = Birch(n_clusters=10)
brc1.fit(X)
assert len(brc1.subcluster_centers_) > 10
assert len(np.unique(brc1.labels_)) == 10
# Test that n_clusters = Agglomerative Clustering gives
# the same results.
gc = AgglomerativeClustering(n_clusters=10)
brc2 = Birch(n_clusters=gc)
brc2.fit(X)
assert_array_equal(brc1.subcluster_labels_, brc2.subcluster_labels_)
assert_array_equal(brc1.labels_, brc2.labels_)
# Test that a small number of clusters raises a warning.
brc4 = Birch(threshold=10000.0)
with pytest.warns(ConvergenceWarning):
brc4.fit(X)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_sparse_X(global_random_seed, global_dtype, csr_container):
# Test that sparse and dense data give same results
X, y = make_blobs(n_samples=100, centers=10, random_state=global_random_seed)
X = X.astype(global_dtype, copy=False)
brc = Birch(n_clusters=10)
brc.fit(X)
csr = csr_container(X)
brc_sparse = Birch(n_clusters=10)
brc_sparse.fit(csr)
# Birch must preserve inputs' dtype
assert brc_sparse.subcluster_centers_.dtype == global_dtype
assert_array_equal(brc.labels_, brc_sparse.labels_)
assert_allclose(brc.subcluster_centers_, brc_sparse.subcluster_centers_)
def test_partial_fit_second_call_error_checks():
# second partial fit calls will error when n_features is not consistent
# with the first call
X, y = make_blobs(n_samples=100)
brc = Birch(n_clusters=3)
brc.partial_fit(X, y)
msg = "X has 1 features, but Birch is expecting 2 features"
with pytest.raises(ValueError, match=msg):
brc.partial_fit(X[:, [0]], y)
def check_branching_factor(node, branching_factor):
subclusters = node.subclusters_
assert branching_factor >= len(subclusters)
for cluster in subclusters:
if cluster.child_:
check_branching_factor(cluster.child_, branching_factor)
def test_branching_factor(global_random_seed, global_dtype):
# Test that nodes have at max branching_factor number of subclusters
X, y = make_blobs(random_state=global_random_seed)
X = X.astype(global_dtype, copy=False)
branching_factor = 9
# Purposefully set a low threshold to maximize the subclusters.
brc = Birch(n_clusters=None, branching_factor=branching_factor, threshold=0.01)
brc.fit(X)
check_branching_factor(brc.root_, branching_factor)
brc = Birch(n_clusters=3, branching_factor=branching_factor, threshold=0.01)
brc.fit(X)
check_branching_factor(brc.root_, branching_factor)
def check_threshold(birch_instance, threshold):
"""Use the leaf linked list for traversal"""
current_leaf = birch_instance.dummy_leaf_.next_leaf_
while current_leaf:
subclusters = current_leaf.subclusters_
for sc in subclusters:
assert threshold >= sc.radius
current_leaf = current_leaf.next_leaf_
def test_threshold(global_random_seed, global_dtype):
# Test that the leaf subclusters have a threshold lesser than radius
X, y = make_blobs(n_samples=80, centers=4, random_state=global_random_seed)
X = X.astype(global_dtype, copy=False)
brc = Birch(threshold=0.5, n_clusters=None)
brc.fit(X)
check_threshold(brc, 0.5)
brc = Birch(threshold=5.0, n_clusters=None)
brc.fit(X)
check_threshold(brc, 5.0)
def test_birch_n_clusters_long_int():
# Check that birch supports n_clusters with np.int64 dtype, for instance
# coming from np.arange. #16484
X, _ = make_blobs(random_state=0)
n_clusters = np.int64(5)
Birch(n_clusters=n_clusters).fit(X)
def test_feature_names_out():
"""Check `get_feature_names_out` for `Birch`."""
X, _ = make_blobs(n_samples=80, n_features=4, random_state=0)
brc = Birch(n_clusters=4)
brc.fit(X)
n_clusters = brc.subcluster_centers_.shape[0]
names_out = brc.get_feature_names_out()
assert_array_equal([f"birch{i}" for i in range(n_clusters)], names_out)
def test_transform_match_across_dtypes(global_random_seed):
X, _ = make_blobs(n_samples=80, n_features=4, random_state=global_random_seed)
brc = Birch(n_clusters=4, threshold=1.1)
Y_64 = brc.fit_transform(X)
Y_32 = brc.fit_transform(X.astype(np.float32))
assert_allclose(Y_64, Y_32, atol=1e-6)
def test_subcluster_dtype(global_dtype):
X = make_blobs(n_samples=80, n_features=4, random_state=0)[0].astype(
global_dtype, copy=False
)
brc = Birch(n_clusters=4)
assert brc.fit(X).subcluster_centers_.dtype == global_dtype
def test_both_subclusters_updated():
"""Check that both subclusters are updated when a node a split, even when there are
duplicated data points. Non-regression test for #23269.
"""
X = np.array(
[
[-2.6192791, -1.5053215],
[-2.9993038, -1.6863596],
[-2.3724914, -1.3438171],
[-2.336792, -1.3417323],
[-2.4089134, -1.3290224],
[-2.3724914, -1.3438171],
[-3.364009, -1.8846745],
[-2.3724914, -1.3438171],
[-2.617677, -1.5003285],
[-2.2960556, -1.3260119],
[-2.3724914, -1.3438171],
[-2.5459878, -1.4533926],
[-2.25979, -1.3003055],
[-2.4089134, -1.3290224],
[-2.3724914, -1.3438171],
[-2.4089134, -1.3290224],
[-2.5459878, -1.4533926],
[-2.3724914, -1.3438171],
[-2.9720619, -1.7058647],
[-2.336792, -1.3417323],
[-2.3724914, -1.3438171],
],
dtype=np.float32,
)
# no error
Birch(branching_factor=5, threshold=1e-5, n_clusters=None).fit(X)

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import numpy as np
import pytest
from sklearn.cluster import BisectingKMeans
from sklearn.metrics import v_measure_score
from sklearn.utils._testing import assert_allclose, assert_array_equal
from sklearn.utils.fixes import CSR_CONTAINERS
@pytest.mark.parametrize("bisecting_strategy", ["biggest_inertia", "largest_cluster"])
@pytest.mark.parametrize("init", ["k-means++", "random"])
def test_three_clusters(bisecting_strategy, init):
"""Tries to perform bisect k-means for three clusters to check
if splitting data is performed correctly.
"""
X = np.array(
[[1, 1], [10, 1], [3, 1], [10, 0], [2, 1], [10, 2], [10, 8], [10, 9], [10, 10]]
)
bisect_means = BisectingKMeans(
n_clusters=3,
random_state=0,
bisecting_strategy=bisecting_strategy,
init=init,
)
bisect_means.fit(X)
expected_centers = [[2, 1], [10, 1], [10, 9]]
expected_labels = [0, 1, 0, 1, 0, 1, 2, 2, 2]
assert_allclose(
sorted(expected_centers), sorted(bisect_means.cluster_centers_.tolist())
)
assert_allclose(v_measure_score(expected_labels, bisect_means.labels_), 1.0)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_sparse(csr_container):
"""Test Bisecting K-Means with sparse data.
Checks if labels and centers are the same between dense and sparse.
"""
rng = np.random.RandomState(0)
X = rng.rand(20, 2)
X[X < 0.8] = 0
X_csr = csr_container(X)
bisect_means = BisectingKMeans(n_clusters=3, random_state=0)
bisect_means.fit(X_csr)
sparse_centers = bisect_means.cluster_centers_
bisect_means.fit(X)
normal_centers = bisect_means.cluster_centers_
# Check if results is the same for dense and sparse data
assert_allclose(normal_centers, sparse_centers, atol=1e-8)
@pytest.mark.parametrize("n_clusters", [4, 5])
def test_n_clusters(n_clusters):
"""Test if resulting labels are in range [0, n_clusters - 1]."""
rng = np.random.RandomState(0)
X = rng.rand(10, 2)
bisect_means = BisectingKMeans(n_clusters=n_clusters, random_state=0)
bisect_means.fit(X)
assert_array_equal(np.unique(bisect_means.labels_), np.arange(n_clusters))
def test_one_cluster():
"""Test single cluster."""
X = np.array([[1, 2], [10, 2], [10, 8]])
bisect_means = BisectingKMeans(n_clusters=1, random_state=0).fit(X)
# All labels from fit or predict should be equal 0
assert all(bisect_means.labels_ == 0)
assert all(bisect_means.predict(X) == 0)
assert_allclose(bisect_means.cluster_centers_, X.mean(axis=0).reshape(1, -1))
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS + [None])
def test_fit_predict(csr_container):
"""Check if labels from fit(X) method are same as from fit(X).predict(X)."""
rng = np.random.RandomState(0)
X = rng.rand(10, 2)
if csr_container is not None:
X[X < 0.8] = 0
X = csr_container(X)
bisect_means = BisectingKMeans(n_clusters=3, random_state=0)
bisect_means.fit(X)
assert_array_equal(bisect_means.labels_, bisect_means.predict(X))
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS + [None])
def test_dtype_preserved(csr_container, global_dtype):
"""Check that centers dtype is the same as input data dtype."""
rng = np.random.RandomState(0)
X = rng.rand(10, 2).astype(global_dtype, copy=False)
if csr_container is not None:
X[X < 0.8] = 0
X = csr_container(X)
km = BisectingKMeans(n_clusters=3, random_state=0)
km.fit(X)
assert km.cluster_centers_.dtype == global_dtype
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS + [None])
def test_float32_float64_equivalence(csr_container):
"""Check that the results are the same between float32 and float64."""
rng = np.random.RandomState(0)
X = rng.rand(10, 2)
if csr_container is not None:
X[X < 0.8] = 0
X = csr_container(X)
km64 = BisectingKMeans(n_clusters=3, random_state=0).fit(X)
km32 = BisectingKMeans(n_clusters=3, random_state=0).fit(X.astype(np.float32))
assert_allclose(km32.cluster_centers_, km64.cluster_centers_)
assert_array_equal(km32.labels_, km64.labels_)
@pytest.mark.parametrize("algorithm", ("lloyd", "elkan"))
def test_no_crash_on_empty_bisections(algorithm):
# Non-regression test for:
# https://github.com/scikit-learn/scikit-learn/issues/27081
rng = np.random.RandomState(0)
X_train = rng.rand(3000, 10)
bkm = BisectingKMeans(n_clusters=10, algorithm=algorithm).fit(X_train)
# predict on scaled data to trigger pathologic case
# where the inner mask leads to empty bisections.
X_test = 50 * rng.rand(100, 10)
labels = bkm.predict(X_test) # should not crash with idiv by 0
assert np.isin(np.unique(labels), np.arange(10)).all()
def test_one_feature():
# Check that no error is raised when there is only one feature
# Non-regression test for:
# https://github.com/scikit-learn/scikit-learn/issues/27236
X = np.random.normal(size=(128, 1))
BisectingKMeans(bisecting_strategy="biggest_inertia", random_state=0).fit(X)

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"""
Tests for DBSCAN clustering algorithm
"""
import pickle
import warnings
import numpy as np
import pytest
from scipy.spatial import distance
from sklearn.cluster import DBSCAN, dbscan
from sklearn.cluster.tests.common import generate_clustered_data
from sklearn.metrics.pairwise import pairwise_distances
from sklearn.neighbors import NearestNeighbors
from sklearn.utils._testing import assert_array_equal
from sklearn.utils.fixes import CSR_CONTAINERS, LIL_CONTAINERS
n_clusters = 3
X = generate_clustered_data(n_clusters=n_clusters)
def test_dbscan_similarity():
# Tests the DBSCAN algorithm with a similarity array.
# Parameters chosen specifically for this task.
eps = 0.15
min_samples = 10
# Compute similarities
D = distance.squareform(distance.pdist(X))
D /= np.max(D)
# Compute DBSCAN
core_samples, labels = dbscan(
D, metric="precomputed", eps=eps, min_samples=min_samples
)
# number of clusters, ignoring noise if present
n_clusters_1 = len(set(labels)) - (1 if -1 in labels else 0)
assert n_clusters_1 == n_clusters
db = DBSCAN(metric="precomputed", eps=eps, min_samples=min_samples)
labels = db.fit(D).labels_
n_clusters_2 = len(set(labels)) - int(-1 in labels)
assert n_clusters_2 == n_clusters
def test_dbscan_feature():
# Tests the DBSCAN algorithm with a feature vector array.
# Parameters chosen specifically for this task.
# Different eps to other test, because distance is not normalised.
eps = 0.8
min_samples = 10
metric = "euclidean"
# Compute DBSCAN
# parameters chosen for task
core_samples, labels = dbscan(X, metric=metric, eps=eps, min_samples=min_samples)
# number of clusters, ignoring noise if present
n_clusters_1 = len(set(labels)) - int(-1 in labels)
assert n_clusters_1 == n_clusters
db = DBSCAN(metric=metric, eps=eps, min_samples=min_samples)
labels = db.fit(X).labels_
n_clusters_2 = len(set(labels)) - int(-1 in labels)
assert n_clusters_2 == n_clusters
@pytest.mark.parametrize("lil_container", LIL_CONTAINERS)
def test_dbscan_sparse(lil_container):
core_sparse, labels_sparse = dbscan(lil_container(X), eps=0.8, min_samples=10)
core_dense, labels_dense = dbscan(X, eps=0.8, min_samples=10)
assert_array_equal(core_dense, core_sparse)
assert_array_equal(labels_dense, labels_sparse)
@pytest.mark.parametrize("include_self", [False, True])
def test_dbscan_sparse_precomputed(include_self):
D = pairwise_distances(X)
nn = NearestNeighbors(radius=0.9).fit(X)
X_ = X if include_self else None
D_sparse = nn.radius_neighbors_graph(X=X_, mode="distance")
# Ensure it is sparse not merely on diagonals:
assert D_sparse.nnz < D.shape[0] * (D.shape[0] - 1)
core_sparse, labels_sparse = dbscan(
D_sparse, eps=0.8, min_samples=10, metric="precomputed"
)
core_dense, labels_dense = dbscan(D, eps=0.8, min_samples=10, metric="precomputed")
assert_array_equal(core_dense, core_sparse)
assert_array_equal(labels_dense, labels_sparse)
def test_dbscan_sparse_precomputed_different_eps():
# test that precomputed neighbors graph is filtered if computed with
# a radius larger than DBSCAN's eps.
lower_eps = 0.2
nn = NearestNeighbors(radius=lower_eps).fit(X)
D_sparse = nn.radius_neighbors_graph(X, mode="distance")
dbscan_lower = dbscan(D_sparse, eps=lower_eps, metric="precomputed")
higher_eps = lower_eps + 0.7
nn = NearestNeighbors(radius=higher_eps).fit(X)
D_sparse = nn.radius_neighbors_graph(X, mode="distance")
dbscan_higher = dbscan(D_sparse, eps=lower_eps, metric="precomputed")
assert_array_equal(dbscan_lower[0], dbscan_higher[0])
assert_array_equal(dbscan_lower[1], dbscan_higher[1])
@pytest.mark.parametrize("metric", ["precomputed", "minkowski"])
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS + [None])
def test_dbscan_input_not_modified(metric, csr_container):
# test that the input is not modified by dbscan
X = np.random.RandomState(0).rand(10, 10)
X = csr_container(X) if csr_container is not None else X
X_copy = X.copy()
dbscan(X, metric=metric)
if csr_container is not None:
assert_array_equal(X.toarray(), X_copy.toarray())
else:
assert_array_equal(X, X_copy)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_dbscan_input_not_modified_precomputed_sparse_nodiag(csr_container):
"""Check that we don't modify in-place the pre-computed sparse matrix.
Non-regression test for:
https://github.com/scikit-learn/scikit-learn/issues/27508
"""
X = np.random.RandomState(0).rand(10, 10)
# Add zeros on the diagonal that will be implicit when creating
# the sparse matrix. If `X` is modified in-place, the zeros from
# the diagonal will be made explicit.
np.fill_diagonal(X, 0)
X = csr_container(X)
assert all(row != col for row, col in zip(*X.nonzero()))
X_copy = X.copy()
dbscan(X, metric="precomputed")
# Make sure that we did not modify `X` in-place even by creating
# explicit 0s values.
assert X.nnz == X_copy.nnz
assert_array_equal(X.toarray(), X_copy.toarray())
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_dbscan_no_core_samples(csr_container):
rng = np.random.RandomState(0)
X = rng.rand(40, 10)
X[X < 0.8] = 0
for X_ in [X, csr_container(X)]:
db = DBSCAN(min_samples=6).fit(X_)
assert_array_equal(db.components_, np.empty((0, X_.shape[1])))
assert_array_equal(db.labels_, -1)
assert db.core_sample_indices_.shape == (0,)
def test_dbscan_callable():
# Tests the DBSCAN algorithm with a callable metric.
# Parameters chosen specifically for this task.
# Different eps to other test, because distance is not normalised.
eps = 0.8
min_samples = 10
# metric is the function reference, not the string key.
metric = distance.euclidean
# Compute DBSCAN
# parameters chosen for task
core_samples, labels = dbscan(
X, metric=metric, eps=eps, min_samples=min_samples, algorithm="ball_tree"
)
# number of clusters, ignoring noise if present
n_clusters_1 = len(set(labels)) - int(-1 in labels)
assert n_clusters_1 == n_clusters
db = DBSCAN(metric=metric, eps=eps, min_samples=min_samples, algorithm="ball_tree")
labels = db.fit(X).labels_
n_clusters_2 = len(set(labels)) - int(-1 in labels)
assert n_clusters_2 == n_clusters
def test_dbscan_metric_params():
# Tests that DBSCAN works with the metrics_params argument.
eps = 0.8
min_samples = 10
p = 1
# Compute DBSCAN with metric_params arg
with warnings.catch_warnings(record=True) as warns:
db = DBSCAN(
metric="minkowski",
metric_params={"p": p},
eps=eps,
p=None,
min_samples=min_samples,
algorithm="ball_tree",
).fit(X)
assert not warns, warns[0].message
core_sample_1, labels_1 = db.core_sample_indices_, db.labels_
# Test that sample labels are the same as passing Minkowski 'p' directly
db = DBSCAN(
metric="minkowski", eps=eps, min_samples=min_samples, algorithm="ball_tree", p=p
).fit(X)
core_sample_2, labels_2 = db.core_sample_indices_, db.labels_
assert_array_equal(core_sample_1, core_sample_2)
assert_array_equal(labels_1, labels_2)
# Minkowski with p=1 should be equivalent to Manhattan distance
db = DBSCAN(
metric="manhattan", eps=eps, min_samples=min_samples, algorithm="ball_tree"
).fit(X)
core_sample_3, labels_3 = db.core_sample_indices_, db.labels_
assert_array_equal(core_sample_1, core_sample_3)
assert_array_equal(labels_1, labels_3)
with pytest.warns(
SyntaxWarning,
match=(
"Parameter p is found in metric_params. "
"The corresponding parameter from __init__ "
"is ignored."
),
):
# Test that checks p is ignored in favor of metric_params={'p': <val>}
db = DBSCAN(
metric="minkowski",
metric_params={"p": p},
eps=eps,
p=p + 1,
min_samples=min_samples,
algorithm="ball_tree",
).fit(X)
core_sample_4, labels_4 = db.core_sample_indices_, db.labels_
assert_array_equal(core_sample_1, core_sample_4)
assert_array_equal(labels_1, labels_4)
def test_dbscan_balltree():
# Tests the DBSCAN algorithm with balltree for neighbor calculation.
eps = 0.8
min_samples = 10
D = pairwise_distances(X)
core_samples, labels = dbscan(
D, metric="precomputed", eps=eps, min_samples=min_samples
)
# number of clusters, ignoring noise if present
n_clusters_1 = len(set(labels)) - int(-1 in labels)
assert n_clusters_1 == n_clusters
db = DBSCAN(p=2.0, eps=eps, min_samples=min_samples, algorithm="ball_tree")
labels = db.fit(X).labels_
n_clusters_2 = len(set(labels)) - int(-1 in labels)
assert n_clusters_2 == n_clusters
db = DBSCAN(p=2.0, eps=eps, min_samples=min_samples, algorithm="kd_tree")
labels = db.fit(X).labels_
n_clusters_3 = len(set(labels)) - int(-1 in labels)
assert n_clusters_3 == n_clusters
db = DBSCAN(p=1.0, eps=eps, min_samples=min_samples, algorithm="ball_tree")
labels = db.fit(X).labels_
n_clusters_4 = len(set(labels)) - int(-1 in labels)
assert n_clusters_4 == n_clusters
db = DBSCAN(leaf_size=20, eps=eps, min_samples=min_samples, algorithm="ball_tree")
labels = db.fit(X).labels_
n_clusters_5 = len(set(labels)) - int(-1 in labels)
assert n_clusters_5 == n_clusters
def test_input_validation():
# DBSCAN.fit should accept a list of lists.
X = [[1.0, 2.0], [3.0, 4.0]]
DBSCAN().fit(X) # must not raise exception
def test_pickle():
obj = DBSCAN()
s = pickle.dumps(obj)
assert type(pickle.loads(s)) is obj.__class__
def test_boundaries():
# ensure min_samples is inclusive of core point
core, _ = dbscan([[0], [1]], eps=2, min_samples=2)
assert 0 in core
# ensure eps is inclusive of circumference
core, _ = dbscan([[0], [1], [1]], eps=1, min_samples=2)
assert 0 in core
core, _ = dbscan([[0], [1], [1]], eps=0.99, min_samples=2)
assert 0 not in core
def test_weighted_dbscan(global_random_seed):
# ensure sample_weight is validated
with pytest.raises(ValueError):
dbscan([[0], [1]], sample_weight=[2])
with pytest.raises(ValueError):
dbscan([[0], [1]], sample_weight=[2, 3, 4])
# ensure sample_weight has an effect
assert_array_equal([], dbscan([[0], [1]], sample_weight=None, min_samples=6)[0])
assert_array_equal([], dbscan([[0], [1]], sample_weight=[5, 5], min_samples=6)[0])
assert_array_equal([0], dbscan([[0], [1]], sample_weight=[6, 5], min_samples=6)[0])
assert_array_equal(
[0, 1], dbscan([[0], [1]], sample_weight=[6, 6], min_samples=6)[0]
)
# points within eps of each other:
assert_array_equal(
[0, 1], dbscan([[0], [1]], eps=1.5, sample_weight=[5, 1], min_samples=6)[0]
)
# and effect of non-positive and non-integer sample_weight:
assert_array_equal(
[], dbscan([[0], [1]], sample_weight=[5, 0], eps=1.5, min_samples=6)[0]
)
assert_array_equal(
[0, 1], dbscan([[0], [1]], sample_weight=[5.9, 0.1], eps=1.5, min_samples=6)[0]
)
assert_array_equal(
[0, 1], dbscan([[0], [1]], sample_weight=[6, 0], eps=1.5, min_samples=6)[0]
)
assert_array_equal(
[], dbscan([[0], [1]], sample_weight=[6, -1], eps=1.5, min_samples=6)[0]
)
# for non-negative sample_weight, cores should be identical to repetition
rng = np.random.RandomState(global_random_seed)
sample_weight = rng.randint(0, 5, X.shape[0])
core1, label1 = dbscan(X, sample_weight=sample_weight)
assert len(label1) == len(X)
X_repeated = np.repeat(X, sample_weight, axis=0)
core_repeated, label_repeated = dbscan(X_repeated)
core_repeated_mask = np.zeros(X_repeated.shape[0], dtype=bool)
core_repeated_mask[core_repeated] = True
core_mask = np.zeros(X.shape[0], dtype=bool)
core_mask[core1] = True
assert_array_equal(np.repeat(core_mask, sample_weight), core_repeated_mask)
# sample_weight should work with precomputed distance matrix
D = pairwise_distances(X)
core3, label3 = dbscan(D, sample_weight=sample_weight, metric="precomputed")
assert_array_equal(core1, core3)
assert_array_equal(label1, label3)
# sample_weight should work with estimator
est = DBSCAN().fit(X, sample_weight=sample_weight)
core4 = est.core_sample_indices_
label4 = est.labels_
assert_array_equal(core1, core4)
assert_array_equal(label1, label4)
est = DBSCAN()
label5 = est.fit_predict(X, sample_weight=sample_weight)
core5 = est.core_sample_indices_
assert_array_equal(core1, core5)
assert_array_equal(label1, label5)
assert_array_equal(label1, est.labels_)
@pytest.mark.parametrize("algorithm", ["brute", "kd_tree", "ball_tree"])
def test_dbscan_core_samples_toy(algorithm):
X = [[0], [2], [3], [4], [6], [8], [10]]
n_samples = len(X)
# Degenerate case: every sample is a core sample, either with its own
# cluster or including other close core samples.
core_samples, labels = dbscan(X, algorithm=algorithm, eps=1, min_samples=1)
assert_array_equal(core_samples, np.arange(n_samples))
assert_array_equal(labels, [0, 1, 1, 1, 2, 3, 4])
# With eps=1 and min_samples=2 only the 3 samples from the denser area
# are core samples. All other points are isolated and considered noise.
core_samples, labels = dbscan(X, algorithm=algorithm, eps=1, min_samples=2)
assert_array_equal(core_samples, [1, 2, 3])
assert_array_equal(labels, [-1, 0, 0, 0, -1, -1, -1])
# Only the sample in the middle of the dense area is core. Its two
# neighbors are edge samples. Remaining samples are noise.
core_samples, labels = dbscan(X, algorithm=algorithm, eps=1, min_samples=3)
assert_array_equal(core_samples, [2])
assert_array_equal(labels, [-1, 0, 0, 0, -1, -1, -1])
# It's no longer possible to extract core samples with eps=1:
# everything is noise.
core_samples, labels = dbscan(X, algorithm=algorithm, eps=1, min_samples=4)
assert_array_equal(core_samples, [])
assert_array_equal(labels, np.full(n_samples, -1.0))
def test_dbscan_precomputed_metric_with_degenerate_input_arrays():
# see https://github.com/scikit-learn/scikit-learn/issues/4641 for
# more details
X = np.eye(10)
labels = DBSCAN(eps=0.5, metric="precomputed").fit(X).labels_
assert len(set(labels)) == 1
X = np.zeros((10, 10))
labels = DBSCAN(eps=0.5, metric="precomputed").fit(X).labels_
assert len(set(labels)) == 1
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_dbscan_precomputed_metric_with_initial_rows_zero(csr_container):
# sample matrix with initial two row all zero
ar = np.array(
[
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0, 0.1, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0, 0.1, 0.0, 0.0],
[0.0, 0.0, 0.1, 0.1, 0.0, 0.0, 0.3],
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.1],
[0.0, 0.0, 0.0, 0.0, 0.3, 0.1, 0.0],
]
)
matrix = csr_container(ar)
labels = DBSCAN(eps=0.2, metric="precomputed", min_samples=2).fit(matrix).labels_
assert_array_equal(labels, [-1, -1, 0, 0, 0, 1, 1])

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"""
Tests for sklearn.cluster._feature_agglomeration
"""
import numpy as np
from numpy.testing import assert_array_equal
from sklearn.cluster import FeatureAgglomeration
from sklearn.datasets import make_blobs
from sklearn.utils._testing import assert_array_almost_equal
def test_feature_agglomeration():
n_clusters = 1
X = np.array([0, 0, 1]).reshape(1, 3) # (n_samples, n_features)
agglo_mean = FeatureAgglomeration(n_clusters=n_clusters, pooling_func=np.mean)
agglo_median = FeatureAgglomeration(n_clusters=n_clusters, pooling_func=np.median)
agglo_mean.fit(X)
agglo_median.fit(X)
assert np.size(np.unique(agglo_mean.labels_)) == n_clusters
assert np.size(np.unique(agglo_median.labels_)) == n_clusters
assert np.size(agglo_mean.labels_) == X.shape[1]
assert np.size(agglo_median.labels_) == X.shape[1]
# Test transform
Xt_mean = agglo_mean.transform(X)
Xt_median = agglo_median.transform(X)
assert Xt_mean.shape[1] == n_clusters
assert Xt_median.shape[1] == n_clusters
assert Xt_mean == np.array([1 / 3.0])
assert Xt_median == np.array([0.0])
# Test inverse transform
X_full_mean = agglo_mean.inverse_transform(Xt_mean)
X_full_median = agglo_median.inverse_transform(Xt_median)
assert np.unique(X_full_mean[0]).size == n_clusters
assert np.unique(X_full_median[0]).size == n_clusters
assert_array_almost_equal(agglo_mean.transform(X_full_mean), Xt_mean)
assert_array_almost_equal(agglo_median.transform(X_full_median), Xt_median)
def test_feature_agglomeration_feature_names_out():
"""Check `get_feature_names_out` for `FeatureAgglomeration`."""
X, _ = make_blobs(n_features=6, random_state=0)
agglo = FeatureAgglomeration(n_clusters=3)
agglo.fit(X)
n_clusters = agglo.n_clusters_
names_out = agglo.get_feature_names_out()
assert_array_equal(
[f"featureagglomeration{i}" for i in range(n_clusters)], names_out
)

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"""
Tests for HDBSCAN clustering algorithm
Based on the DBSCAN test code
"""
import numpy as np
import pytest
from scipy import stats
from scipy.spatial import distance
from sklearn.cluster import HDBSCAN
from sklearn.cluster._hdbscan._tree import (
CONDENSED_dtype,
_condense_tree,
_do_labelling,
)
from sklearn.cluster._hdbscan.hdbscan import _OUTLIER_ENCODING
from sklearn.datasets import make_blobs
from sklearn.metrics import fowlkes_mallows_score
from sklearn.metrics.pairwise import _VALID_METRICS, euclidean_distances
from sklearn.neighbors import BallTree, KDTree
from sklearn.preprocessing import StandardScaler
from sklearn.utils import shuffle
from sklearn.utils._testing import assert_allclose, assert_array_equal
from sklearn.utils.fixes import CSC_CONTAINERS, CSR_CONTAINERS
X, y = make_blobs(n_samples=200, random_state=10)
X, y = shuffle(X, y, random_state=7)
X = StandardScaler().fit_transform(X)
ALGORITHMS = [
"kd_tree",
"ball_tree",
"brute",
"auto",
]
OUTLIER_SET = {-1} | {out["label"] for _, out in _OUTLIER_ENCODING.items()}
def check_label_quality(labels, threshold=0.99):
n_clusters = len(set(labels) - OUTLIER_SET)
assert n_clusters == 3
assert fowlkes_mallows_score(labels, y) > threshold
@pytest.mark.parametrize("outlier_type", _OUTLIER_ENCODING)
def test_outlier_data(outlier_type):
"""
Tests if np.inf and np.nan data are each treated as special outliers.
"""
outlier = {
"infinite": np.inf,
"missing": np.nan,
}[outlier_type]
prob_check = {
"infinite": lambda x, y: x == y,
"missing": lambda x, y: np.isnan(x),
}[outlier_type]
label = _OUTLIER_ENCODING[outlier_type]["label"]
prob = _OUTLIER_ENCODING[outlier_type]["prob"]
X_outlier = X.copy()
X_outlier[0] = [outlier, 1]
X_outlier[5] = [outlier, outlier]
model = HDBSCAN(copy=False).fit(X_outlier)
(missing_labels_idx,) = (model.labels_ == label).nonzero()
assert_array_equal(missing_labels_idx, [0, 5])
(missing_probs_idx,) = (prob_check(model.probabilities_, prob)).nonzero()
assert_array_equal(missing_probs_idx, [0, 5])
clean_indices = list(range(1, 5)) + list(range(6, 200))
clean_model = HDBSCAN(copy=False).fit(X_outlier[clean_indices])
assert_array_equal(clean_model.labels_, model.labels_[clean_indices])
def test_hdbscan_distance_matrix():
"""
Tests that HDBSCAN works with precomputed distance matrices, and throws the
appropriate errors when needed.
"""
D = euclidean_distances(X)
D_original = D.copy()
labels = HDBSCAN(metric="precomputed", copy=True).fit_predict(D)
assert_allclose(D, D_original)
check_label_quality(labels)
msg = r"The precomputed distance matrix.*has shape"
with pytest.raises(ValueError, match=msg):
HDBSCAN(metric="precomputed", copy=True).fit_predict(X)
msg = r"The precomputed distance matrix.*values"
# Ensure the matrix is not symmetric
D[0, 1] = 10
D[1, 0] = 1
with pytest.raises(ValueError, match=msg):
HDBSCAN(metric="precomputed", copy=False).fit_predict(D)
@pytest.mark.parametrize("sparse_constructor", [*CSR_CONTAINERS, *CSC_CONTAINERS])
def test_hdbscan_sparse_distance_matrix(sparse_constructor):
"""
Tests that HDBSCAN works with sparse distance matrices.
"""
D = distance.squareform(distance.pdist(X))
D /= np.max(D)
threshold = stats.scoreatpercentile(D.flatten(), 50)
D[D >= threshold] = 0.0
D = sparse_constructor(D)
D.eliminate_zeros()
labels = HDBSCAN(metric="precomputed", copy=False).fit_predict(D)
check_label_quality(labels)
def test_hdbscan_feature_array():
"""
Tests that HDBSCAN works with feature array, including an arbitrary
goodness of fit check. Note that the check is a simple heuristic.
"""
labels = HDBSCAN(copy=False).fit_predict(X)
# Check that clustering is arbitrarily good
# This is a heuristic to guard against regression
check_label_quality(labels)
@pytest.mark.parametrize("algo", ALGORITHMS)
@pytest.mark.parametrize("metric", _VALID_METRICS)
def test_hdbscan_algorithms(algo, metric):
"""
Tests that HDBSCAN works with the expected combinations of algorithms and
metrics, or raises the expected errors.
"""
labels = HDBSCAN(algorithm=algo, copy=False).fit_predict(X)
check_label_quality(labels)
# Validation for brute is handled by `pairwise_distances`
if algo in ("brute", "auto"):
return
ALGOS_TREES = {
"kd_tree": KDTree,
"ball_tree": BallTree,
}
metric_params = {
"mahalanobis": {"V": np.eye(X.shape[1])},
"seuclidean": {"V": np.ones(X.shape[1])},
"minkowski": {"p": 2},
"wminkowski": {"p": 2, "w": np.ones(X.shape[1])},
}.get(metric, None)
hdb = HDBSCAN(
algorithm=algo,
metric=metric,
metric_params=metric_params,
copy=False,
)
if metric not in ALGOS_TREES[algo].valid_metrics:
with pytest.raises(ValueError):
hdb.fit(X)
elif metric == "wminkowski":
with pytest.warns(FutureWarning):
hdb.fit(X)
else:
hdb.fit(X)
def test_dbscan_clustering():
"""
Tests that HDBSCAN can generate a sufficiently accurate dbscan clustering.
This test is more of a sanity check than a rigorous evaluation.
"""
clusterer = HDBSCAN(copy=False).fit(X)
labels = clusterer.dbscan_clustering(0.3)
# We use a looser threshold due to dbscan producing a more constrained
# clustering representation
check_label_quality(labels, threshold=0.92)
@pytest.mark.parametrize("cut_distance", (0.1, 0.5, 1))
def test_dbscan_clustering_outlier_data(cut_distance):
"""
Tests if np.inf and np.nan data are each treated as special outliers.
"""
missing_label = _OUTLIER_ENCODING["missing"]["label"]
infinite_label = _OUTLIER_ENCODING["infinite"]["label"]
X_outlier = X.copy()
X_outlier[0] = [np.inf, 1]
X_outlier[2] = [1, np.nan]
X_outlier[5] = [np.inf, np.nan]
model = HDBSCAN(copy=False).fit(X_outlier)
labels = model.dbscan_clustering(cut_distance=cut_distance)
missing_labels_idx = np.flatnonzero(labels == missing_label)
assert_array_equal(missing_labels_idx, [2, 5])
infinite_labels_idx = np.flatnonzero(labels == infinite_label)
assert_array_equal(infinite_labels_idx, [0])
clean_idx = list(set(range(200)) - set(missing_labels_idx + infinite_labels_idx))
clean_model = HDBSCAN(copy=False).fit(X_outlier[clean_idx])
clean_labels = clean_model.dbscan_clustering(cut_distance=cut_distance)
assert_array_equal(clean_labels, labels[clean_idx])
def test_hdbscan_best_balltree_metric():
"""
Tests that HDBSCAN using `BallTree` works.
"""
labels = HDBSCAN(
metric="seuclidean", metric_params={"V": np.ones(X.shape[1])}, copy=False
).fit_predict(X)
check_label_quality(labels)
def test_hdbscan_no_clusters():
"""
Tests that HDBSCAN correctly does not generate a valid cluster when the
`min_cluster_size` is too large for the data.
"""
labels = HDBSCAN(min_cluster_size=len(X) - 1, copy=False).fit_predict(X)
assert set(labels).issubset(OUTLIER_SET)
def test_hdbscan_min_cluster_size():
"""
Test that the smallest non-noise cluster has at least `min_cluster_size`
many points
"""
for min_cluster_size in range(2, len(X), 1):
labels = HDBSCAN(min_cluster_size=min_cluster_size, copy=False).fit_predict(X)
true_labels = [label for label in labels if label != -1]
if len(true_labels) != 0:
assert np.min(np.bincount(true_labels)) >= min_cluster_size
def test_hdbscan_callable_metric():
"""
Tests that HDBSCAN works when passed a callable metric.
"""
metric = distance.euclidean
labels = HDBSCAN(metric=metric, copy=False).fit_predict(X)
check_label_quality(labels)
@pytest.mark.parametrize("tree", ["kd_tree", "ball_tree"])
def test_hdbscan_precomputed_non_brute(tree):
"""
Tests that HDBSCAN correctly raises an error when passing precomputed data
while requesting a tree-based algorithm.
"""
hdb = HDBSCAN(metric="precomputed", algorithm=tree, copy=False)
msg = "precomputed is not a valid metric for"
with pytest.raises(ValueError, match=msg):
hdb.fit(X)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_hdbscan_sparse(csr_container):
"""
Tests that HDBSCAN works correctly when passing sparse feature data.
Evaluates correctness by comparing against the same data passed as a dense
array.
"""
dense_labels = HDBSCAN(copy=False).fit(X).labels_
check_label_quality(dense_labels)
_X_sparse = csr_container(X)
X_sparse = _X_sparse.copy()
sparse_labels = HDBSCAN(copy=False).fit(X_sparse).labels_
assert_array_equal(dense_labels, sparse_labels)
# Compare that the sparse and dense non-precomputed routines return the same labels
# where the 0th observation contains the outlier.
for outlier_val, outlier_type in ((np.inf, "infinite"), (np.nan, "missing")):
X_dense = X.copy()
X_dense[0, 0] = outlier_val
dense_labels = HDBSCAN(copy=False).fit(X_dense).labels_
check_label_quality(dense_labels)
assert dense_labels[0] == _OUTLIER_ENCODING[outlier_type]["label"]
X_sparse = _X_sparse.copy()
X_sparse[0, 0] = outlier_val
sparse_labels = HDBSCAN(copy=False).fit(X_sparse).labels_
assert_array_equal(dense_labels, sparse_labels)
msg = "Sparse data matrices only support algorithm `brute`."
with pytest.raises(ValueError, match=msg):
HDBSCAN(metric="euclidean", algorithm="ball_tree", copy=False).fit(X_sparse)
@pytest.mark.parametrize("algorithm", ALGORITHMS)
def test_hdbscan_centers(algorithm):
"""
Tests that HDBSCAN centers are calculated and stored properly, and are
accurate to the data.
"""
centers = [(0.0, 0.0), (3.0, 3.0)]
H, _ = make_blobs(n_samples=2000, random_state=0, centers=centers, cluster_std=0.5)
hdb = HDBSCAN(store_centers="both", copy=False).fit(H)
for center, centroid, medoid in zip(centers, hdb.centroids_, hdb.medoids_):
assert_allclose(center, centroid, rtol=1, atol=0.05)
assert_allclose(center, medoid, rtol=1, atol=0.05)
# Ensure that nothing is done for noise
hdb = HDBSCAN(
algorithm=algorithm,
store_centers="both",
min_cluster_size=X.shape[0],
copy=False,
).fit(X)
assert hdb.centroids_.shape[0] == 0
assert hdb.medoids_.shape[0] == 0
def test_hdbscan_allow_single_cluster_with_epsilon():
"""
Tests that HDBSCAN single-cluster selection with epsilon works correctly.
"""
rng = np.random.RandomState(0)
no_structure = rng.rand(150, 2)
# without epsilon we should see many noise points as children of root.
labels = HDBSCAN(
min_cluster_size=5,
cluster_selection_epsilon=0.0,
cluster_selection_method="eom",
allow_single_cluster=True,
copy=False,
).fit_predict(no_structure)
unique_labels, counts = np.unique(labels, return_counts=True)
assert len(unique_labels) == 2
# Arbitrary heuristic. Would prefer something more precise.
assert counts[unique_labels == -1] > 30
# for this random seed an epsilon of 0.18 will produce exactly 2 noise
# points at that cut in single linkage.
labels = HDBSCAN(
min_cluster_size=5,
cluster_selection_epsilon=0.18,
cluster_selection_method="eom",
allow_single_cluster=True,
algorithm="kd_tree",
copy=False,
).fit_predict(no_structure)
unique_labels, counts = np.unique(labels, return_counts=True)
assert len(unique_labels) == 2
assert counts[unique_labels == -1] == 2
def test_hdbscan_better_than_dbscan():
"""
Validate that HDBSCAN can properly cluster this difficult synthetic
dataset. Note that DBSCAN fails on this (see HDBSCAN plotting
example)
"""
centers = [[-0.85, -0.85], [-0.85, 0.85], [3, 3], [3, -3]]
X, y = make_blobs(
n_samples=750,
centers=centers,
cluster_std=[0.2, 0.35, 1.35, 1.35],
random_state=0,
)
labels = HDBSCAN(copy=False).fit(X).labels_
n_clusters = len(set(labels)) - int(-1 in labels)
assert n_clusters == 4
fowlkes_mallows_score(labels, y) > 0.99
@pytest.mark.parametrize(
"kwargs, X",
[
({"metric": "precomputed"}, np.array([[1, np.inf], [np.inf, 1]])),
({"metric": "precomputed"}, [[1, 2], [2, 1]]),
({}, [[1, 2], [3, 4]]),
],
)
def test_hdbscan_usable_inputs(X, kwargs):
"""
Tests that HDBSCAN works correctly for array-likes and precomputed inputs
with non-finite points.
"""
HDBSCAN(min_samples=1, copy=False, **kwargs).fit(X)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_hdbscan_sparse_distances_too_few_nonzero(csr_container):
"""
Tests that HDBSCAN raises the correct error when there are too few
non-zero distances.
"""
X = csr_container(np.zeros((10, 10)))
msg = "There exists points with fewer than"
with pytest.raises(ValueError, match=msg):
HDBSCAN(metric="precomputed", copy=False).fit(X)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_hdbscan_sparse_distances_disconnected_graph(csr_container):
"""
Tests that HDBSCAN raises the correct error when the distance matrix
has multiple connected components.
"""
# Create symmetric sparse matrix with 2 connected components
X = np.zeros((20, 20))
X[:5, :5] = 1
X[5:, 15:] = 1
X = X + X.T
X = csr_container(X)
msg = "HDBSCAN cannot be performed on a disconnected graph"
with pytest.raises(ValueError, match=msg):
HDBSCAN(metric="precomputed", copy=False).fit(X)
def test_hdbscan_tree_invalid_metric():
"""
Tests that HDBSCAN correctly raises an error for invalid metric choices.
"""
metric_callable = lambda x: x
msg = (
".* is not a valid metric for a .*-based algorithm\\. Please select a different"
" metric\\."
)
# Callables are not supported for either
with pytest.raises(ValueError, match=msg):
HDBSCAN(algorithm="kd_tree", metric=metric_callable, copy=False).fit(X)
with pytest.raises(ValueError, match=msg):
HDBSCAN(algorithm="ball_tree", metric=metric_callable, copy=False).fit(X)
# The set of valid metrics for KDTree at the time of writing this test is a
# strict subset of those supported in BallTree
metrics_not_kd = list(set(BallTree.valid_metrics) - set(KDTree.valid_metrics))
if len(metrics_not_kd) > 0:
with pytest.raises(ValueError, match=msg):
HDBSCAN(algorithm="kd_tree", metric=metrics_not_kd[0], copy=False).fit(X)
def test_hdbscan_too_many_min_samples():
"""
Tests that HDBSCAN correctly raises an error when setting `min_samples`
larger than the number of samples.
"""
hdb = HDBSCAN(min_samples=len(X) + 1, copy=False)
msg = r"min_samples (.*) must be at most"
with pytest.raises(ValueError, match=msg):
hdb.fit(X)
def test_hdbscan_precomputed_dense_nan():
"""
Tests that HDBSCAN correctly raises an error when providing precomputed
distances with `np.nan` values.
"""
X_nan = X.copy()
X_nan[0, 0] = np.nan
msg = "np.nan values found in precomputed-dense"
hdb = HDBSCAN(metric="precomputed", copy=False)
with pytest.raises(ValueError, match=msg):
hdb.fit(X_nan)
@pytest.mark.parametrize("allow_single_cluster", [True, False])
@pytest.mark.parametrize("epsilon", [0, 0.1])
def test_labelling_distinct(global_random_seed, allow_single_cluster, epsilon):
"""
Tests that the `_do_labelling` helper function correctly assigns labels.
"""
n_samples = 48
X, y = make_blobs(
n_samples,
random_state=global_random_seed,
# Ensure the clusters are distinct with no overlap
centers=[
[0, 0],
[10, 0],
[0, 10],
],
)
est = HDBSCAN(copy=False).fit(X)
condensed_tree = _condense_tree(
est._single_linkage_tree_, min_cluster_size=est.min_cluster_size
)
clusters = {n_samples + 2, n_samples + 3, n_samples + 4}
cluster_label_map = {n_samples + 2: 0, n_samples + 3: 1, n_samples + 4: 2}
labels = _do_labelling(
condensed_tree=condensed_tree,
clusters=clusters,
cluster_label_map=cluster_label_map,
allow_single_cluster=allow_single_cluster,
cluster_selection_epsilon=epsilon,
)
first_with_label = {_y: np.where(y == _y)[0][0] for _y in list(set(y))}
y_to_labels = {_y: labels[first_with_label[_y]] for _y in list(set(y))}
aligned_target = np.vectorize(y_to_labels.get)(y)
assert_array_equal(labels, aligned_target)
def test_labelling_thresholding():
"""
Tests that the `_do_labelling` helper function correctly thresholds the
incoming lambda values given various `cluster_selection_epsilon` values.
"""
n_samples = 5
MAX_LAMBDA = 1.5
condensed_tree = np.array(
[
(5, 2, MAX_LAMBDA, 1),
(5, 1, 0.1, 1),
(5, 0, MAX_LAMBDA, 1),
(5, 3, 0.2, 1),
(5, 4, 0.3, 1),
],
dtype=CONDENSED_dtype,
)
labels = _do_labelling(
condensed_tree=condensed_tree,
clusters={n_samples},
cluster_label_map={n_samples: 0, n_samples + 1: 1},
allow_single_cluster=True,
cluster_selection_epsilon=1,
)
num_noise = condensed_tree["value"] < 1
assert sum(num_noise) == sum(labels == -1)
labels = _do_labelling(
condensed_tree=condensed_tree,
clusters={n_samples},
cluster_label_map={n_samples: 0, n_samples + 1: 1},
allow_single_cluster=True,
cluster_selection_epsilon=0,
)
# The threshold should be calculated per-sample based on the largest
# lambda of any simbling node. In this case, all points are siblings
# and the largest value is exactly MAX_LAMBDA.
num_noise = condensed_tree["value"] < MAX_LAMBDA
assert sum(num_noise) == sum(labels == -1)
@pytest.mark.parametrize("store_centers", ["centroid", "medoid"])
def test_hdbscan_error_precomputed_and_store_centers(store_centers):
"""Check that we raise an error if the centers are requested together with
a precomputed input matrix.
Non-regression test for:
https://github.com/scikit-learn/scikit-learn/issues/27893
"""
rng = np.random.RandomState(0)
X = rng.random((100, 2))
X_dist = euclidean_distances(X)
err_msg = "Cannot store centers when using a precomputed distance matrix."
with pytest.raises(ValueError, match=err_msg):
HDBSCAN(
metric="precomputed",
store_centers=store_centers,
copy=False,
).fit(X_dist)
@pytest.mark.parametrize("valid_algo", ["auto", "brute"])
def test_hdbscan_cosine_metric_valid_algorithm(valid_algo):
"""Test that HDBSCAN works with the "cosine" metric when the algorithm is set
to "brute" or "auto".
Non-regression test for issue #28631
"""
HDBSCAN(metric="cosine", algorithm=valid_algo, copy=False).fit_predict(X)
@pytest.mark.parametrize("invalid_algo", ["kd_tree", "ball_tree"])
def test_hdbscan_cosine_metric_invalid_algorithm(invalid_algo):
"""Test that HDBSCAN raises an informative error is raised when an unsupported
algorithm is used with the "cosine" metric.
"""
hdbscan = HDBSCAN(metric="cosine", algorithm=invalid_algo, copy=False)
with pytest.raises(ValueError, match="cosine is not a valid metric"):
hdbscan.fit_predict(X)
# TODO(1.10): remove this test
def test_hdbscan_default_copy_warning():
"""
Test that HDBSCAN raises a FutureWarning when the `copy`
parameter is not set.
"""
X = np.random.RandomState(0).random((100, 2))
msg = r"The default value of `copy` will change from False to True in 1.10."
with pytest.warns(FutureWarning, match=msg):
hdb = HDBSCAN(min_cluster_size=20)
hdb.fit(X)

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@@ -0,0 +1,889 @@
"""
Several basic tests for hierarchical clustering procedures
"""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import itertools
import shutil
from functools import partial
from tempfile import mkdtemp
import numpy as np
import pytest
from scipy.cluster import hierarchy
from scipy.sparse.csgraph import connected_components
from sklearn.cluster import AgglomerativeClustering, FeatureAgglomeration, ward_tree
from sklearn.cluster._agglomerative import (
_TREE_BUILDERS,
_fix_connectivity,
_hc_cut,
linkage_tree,
)
from sklearn.cluster._hierarchical_fast import (
average_merge,
max_merge,
mst_linkage_core,
)
from sklearn.datasets import make_circles, make_moons
from sklearn.feature_extraction.image import grid_to_graph
from sklearn.metrics import DistanceMetric
from sklearn.metrics.cluster import adjusted_rand_score, normalized_mutual_info_score
from sklearn.metrics.pairwise import (
PAIRED_DISTANCES,
cosine_distances,
manhattan_distances,
pairwise_distances,
)
from sklearn.metrics.tests.test_dist_metrics import METRICS_DEFAULT_PARAMS
from sklearn.neighbors import kneighbors_graph
from sklearn.utils._fast_dict import IntFloatDict
from sklearn.utils._testing import (
assert_almost_equal,
assert_array_almost_equal,
assert_array_equal,
create_memmap_backed_data,
ignore_warnings,
)
from sklearn.utils.fixes import LIL_CONTAINERS
def test_linkage_misc():
# Misc tests on linkage
rng = np.random.RandomState(42)
X = rng.normal(size=(5, 5))
with pytest.raises(ValueError):
linkage_tree(X, linkage="foo")
with pytest.raises(ValueError):
linkage_tree(X, connectivity=np.ones((4, 4)))
# Smoke test FeatureAgglomeration
FeatureAgglomeration().fit(X)
# test hierarchical clustering on a precomputed distances matrix
dis = cosine_distances(X)
res = linkage_tree(dis, affinity="precomputed")
assert_array_equal(res[0], linkage_tree(X, affinity="cosine")[0])
# test hierarchical clustering on a precomputed distances matrix
res = linkage_tree(X, affinity=manhattan_distances)
assert_array_equal(res[0], linkage_tree(X, affinity="manhattan")[0])
def test_structured_linkage_tree():
# Check that we obtain the correct solution for structured linkage trees.
rng = np.random.RandomState(0)
mask = np.ones([10, 10], dtype=bool)
# Avoiding a mask with only 'True' entries
mask[4:7, 4:7] = 0
X = rng.randn(50, 100)
connectivity = grid_to_graph(*mask.shape)
for tree_builder in _TREE_BUILDERS.values():
children, n_components, n_leaves, parent = tree_builder(
X.T, connectivity=connectivity
)
n_nodes = 2 * X.shape[1] - 1
assert len(children) + n_leaves == n_nodes
# Check that ward_tree raises a ValueError with a connectivity matrix
# of the wrong shape
with pytest.raises(ValueError):
tree_builder(X.T, connectivity=np.ones((4, 4)))
# Check that fitting with no samples raises an error
with pytest.raises(ValueError):
tree_builder(X.T[:0], connectivity=connectivity)
def test_unstructured_linkage_tree():
# Check that we obtain the correct solution for unstructured linkage trees.
rng = np.random.RandomState(0)
X = rng.randn(50, 100)
for this_X in (X, X[0]):
# With specified a number of clusters just for the sake of
# raising a warning and testing the warning code
with ignore_warnings():
with pytest.warns(UserWarning):
children, n_nodes, n_leaves, parent = ward_tree(this_X.T, n_clusters=10)
n_nodes = 2 * X.shape[1] - 1
assert len(children) + n_leaves == n_nodes
for tree_builder in _TREE_BUILDERS.values():
for this_X in (X, X[0]):
with ignore_warnings():
with pytest.warns(UserWarning):
children, n_nodes, n_leaves, parent = tree_builder(
this_X.T, n_clusters=10
)
n_nodes = 2 * X.shape[1] - 1
assert len(children) + n_leaves == n_nodes
def test_height_linkage_tree():
# Check that the height of the results of linkage tree is sorted.
rng = np.random.RandomState(0)
mask = np.ones([10, 10], dtype=bool)
X = rng.randn(50, 100)
connectivity = grid_to_graph(*mask.shape)
for linkage_func in _TREE_BUILDERS.values():
children, n_nodes, n_leaves, parent = linkage_func(
X.T, connectivity=connectivity
)
n_nodes = 2 * X.shape[1] - 1
assert len(children) + n_leaves == n_nodes
def test_zero_cosine_linkage_tree():
# Check that zero vectors in X produce an error when
# 'cosine' affinity is used
X = np.array([[0, 1], [0, 0]])
msg = "Cosine affinity cannot be used when X contains zero vectors"
with pytest.raises(ValueError, match=msg):
linkage_tree(X, affinity="cosine")
@pytest.mark.parametrize("n_clusters, distance_threshold", [(None, 0.5), (10, None)])
@pytest.mark.parametrize("compute_distances", [True, False])
@pytest.mark.parametrize("linkage", ["ward", "complete", "average", "single"])
def test_agglomerative_clustering_distances(
n_clusters, compute_distances, distance_threshold, linkage
):
# Check that when `compute_distances` is True or `distance_threshold` is
# given, the fitted model has an attribute `distances_`.
rng = np.random.RandomState(0)
mask = np.ones([10, 10], dtype=bool)
n_samples = 100
X = rng.randn(n_samples, 50)
connectivity = grid_to_graph(*mask.shape)
clustering = AgglomerativeClustering(
n_clusters=n_clusters,
connectivity=connectivity,
linkage=linkage,
distance_threshold=distance_threshold,
compute_distances=compute_distances,
)
clustering.fit(X)
if compute_distances or (distance_threshold is not None):
assert hasattr(clustering, "distances_")
n_children = clustering.children_.shape[0]
n_nodes = n_children + 1
assert clustering.distances_.shape == (n_nodes - 1,)
else:
assert not hasattr(clustering, "distances_")
@pytest.mark.parametrize("lil_container", LIL_CONTAINERS)
def test_agglomerative_clustering(global_random_seed, lil_container):
# Check that we obtain the correct number of clusters with
# agglomerative clustering.
rng = np.random.RandomState(global_random_seed)
mask = np.ones([10, 10], dtype=bool)
n_samples = 100
X = rng.randn(n_samples, 50)
connectivity = grid_to_graph(*mask.shape)
for linkage in ("ward", "complete", "average", "single"):
clustering = AgglomerativeClustering(
n_clusters=10, connectivity=connectivity, linkage=linkage
)
clustering.fit(X)
# test caching
try:
tempdir = mkdtemp()
clustering = AgglomerativeClustering(
n_clusters=10,
connectivity=connectivity,
memory=tempdir,
linkage=linkage,
)
clustering.fit(X)
labels = clustering.labels_
assert np.size(np.unique(labels)) == 10
finally:
shutil.rmtree(tempdir)
# Turn caching off now
clustering = AgglomerativeClustering(
n_clusters=10, connectivity=connectivity, linkage=linkage
)
# Check that we obtain the same solution with early-stopping of the
# tree building
clustering.compute_full_tree = False
clustering.fit(X)
assert_almost_equal(normalized_mutual_info_score(clustering.labels_, labels), 1)
clustering.connectivity = None
clustering.fit(X)
assert np.size(np.unique(clustering.labels_)) == 10
# Check that we raise a TypeError on dense matrices
clustering = AgglomerativeClustering(
n_clusters=10,
connectivity=lil_container(connectivity.toarray()[:10, :10]),
linkage=linkage,
)
with pytest.raises(ValueError):
clustering.fit(X)
# Test that using ward with another metric than euclidean raises an
# exception
clustering = AgglomerativeClustering(
n_clusters=10,
connectivity=connectivity.toarray(),
metric="manhattan",
linkage="ward",
)
with pytest.raises(ValueError):
clustering.fit(X)
# Test using another metric than euclidean works with linkage complete
for metric in PAIRED_DISTANCES.keys():
# Compare our (structured) implementation to scipy
clustering = AgglomerativeClustering(
n_clusters=10,
connectivity=np.ones((n_samples, n_samples)),
metric=metric,
linkage="complete",
)
clustering.fit(X)
clustering2 = AgglomerativeClustering(
n_clusters=10, connectivity=None, metric=metric, linkage="complete"
)
clustering2.fit(X)
assert_almost_equal(
normalized_mutual_info_score(clustering2.labels_, clustering.labels_), 1
)
# Test that using a distance matrix (affinity = 'precomputed') has same
# results (with connectivity constraints)
clustering = AgglomerativeClustering(
n_clusters=10, connectivity=connectivity, linkage="complete"
)
clustering.fit(X)
X_dist = pairwise_distances(X)
clustering2 = AgglomerativeClustering(
n_clusters=10,
connectivity=connectivity,
metric="precomputed",
linkage="complete",
)
clustering2.fit(X_dist)
assert_array_equal(clustering.labels_, clustering2.labels_)
def test_agglomerative_clustering_memory_mapped():
"""AgglomerativeClustering must work on mem-mapped dataset.
Non-regression test for issue #19875.
"""
rng = np.random.RandomState(0)
Xmm = create_memmap_backed_data(rng.randn(50, 100))
AgglomerativeClustering(metric="euclidean", linkage="single").fit(Xmm)
def test_ward_agglomeration(global_random_seed):
# Check that we obtain the correct solution in a simplistic case
rng = np.random.RandomState(global_random_seed)
mask = np.ones([10, 10], dtype=bool)
X = rng.randn(50, 100)
connectivity = grid_to_graph(*mask.shape)
agglo = FeatureAgglomeration(n_clusters=5, connectivity=connectivity)
agglo.fit(X)
assert np.size(np.unique(agglo.labels_)) == 5
X_red = agglo.transform(X)
assert X_red.shape[1] == 5
X_full = agglo.inverse_transform(X_red)
assert np.unique(X_full[0]).size == 5
assert_array_almost_equal(agglo.transform(X_full), X_red)
# Check that fitting with no samples raises a ValueError
with pytest.raises(ValueError):
agglo.fit(X[:0])
def test_single_linkage_clustering():
# Check that we get the correct result in two emblematic cases
moons, moon_labels = make_moons(noise=0.05, random_state=42)
clustering = AgglomerativeClustering(n_clusters=2, linkage="single")
clustering.fit(moons)
assert_almost_equal(
normalized_mutual_info_score(clustering.labels_, moon_labels), 1
)
circles, circle_labels = make_circles(factor=0.5, noise=0.025, random_state=42)
clustering = AgglomerativeClustering(n_clusters=2, linkage="single")
clustering.fit(circles)
assert_almost_equal(
normalized_mutual_info_score(clustering.labels_, circle_labels), 1
)
def assess_same_labelling(cut1, cut2):
"""Util for comparison with scipy"""
co_clust = []
for cut in [cut1, cut2]:
n = len(cut)
k = cut.max() + 1
ecut = np.zeros((n, k))
ecut[np.arange(n), cut] = 1
co_clust.append(np.dot(ecut, ecut.T))
assert (co_clust[0] == co_clust[1]).all()
def test_sparse_scikit_vs_scipy(global_random_seed):
# Test scikit linkage with full connectivity (i.e. unstructured) vs scipy
n, p, k = 10, 5, 3
rng = np.random.RandomState(global_random_seed)
# Not using a lil_matrix here, just to check that non sparse
# matrices are well handled
connectivity = np.ones((n, n))
for linkage in _TREE_BUILDERS.keys():
for i in range(5):
X = 0.1 * rng.normal(size=(n, p))
X -= 4.0 * np.arange(n)[:, np.newaxis]
X -= X.mean(axis=1)[:, np.newaxis]
out = hierarchy.linkage(X, method=linkage)
children_ = out[:, :2].astype(int, copy=False)
children, _, n_leaves, _ = _TREE_BUILDERS[linkage](
X, connectivity=connectivity
)
# Sort the order of child nodes per row for consistency
children.sort(axis=1)
assert_array_equal(
children,
children_,
"linkage tree differs from scipy impl for linkage: " + linkage,
)
cut = _hc_cut(k, children, n_leaves)
cut_ = _hc_cut(k, children_, n_leaves)
assess_same_labelling(cut, cut_)
# Test error management in _hc_cut
with pytest.raises(ValueError):
_hc_cut(n_leaves + 1, children, n_leaves)
# Make sure our custom mst_linkage_core gives
# the same results as scipy's builtin
def test_vector_scikit_single_vs_scipy_single(global_random_seed):
n_samples, n_features, n_clusters = 10, 5, 3
rng = np.random.RandomState(global_random_seed)
X = 0.1 * rng.normal(size=(n_samples, n_features))
X -= 4.0 * np.arange(n_samples)[:, np.newaxis]
X -= X.mean(axis=1)[:, np.newaxis]
out = hierarchy.linkage(X, method="single")
children_scipy = out[:, :2].astype(int)
children, _, n_leaves, _ = _TREE_BUILDERS["single"](X)
# Sort the order of child nodes per row for consistency
children.sort(axis=1)
assert_array_equal(
children,
children_scipy,
"linkage tree differs from scipy impl for single linkage.",
)
cut = _hc_cut(n_clusters, children, n_leaves)
cut_scipy = _hc_cut(n_clusters, children_scipy, n_leaves)
assess_same_labelling(cut, cut_scipy)
@pytest.mark.parametrize("metric_param_grid", METRICS_DEFAULT_PARAMS)
def test_mst_linkage_core_memory_mapped(metric_param_grid):
"""The MST-LINKAGE-CORE algorithm must work on mem-mapped dataset.
Non-regression test for issue #19875.
"""
rng = np.random.RandomState(seed=1)
X = rng.normal(size=(20, 4))
Xmm = create_memmap_backed_data(X)
metric, param_grid = metric_param_grid
keys = param_grid.keys()
for vals in itertools.product(*param_grid.values()):
kwargs = dict(zip(keys, vals))
distance_metric = DistanceMetric.get_metric(metric, **kwargs)
mst = mst_linkage_core(X, distance_metric)
mst_mm = mst_linkage_core(Xmm, distance_metric)
np.testing.assert_equal(mst, mst_mm)
def test_identical_points():
# Ensure identical points are handled correctly when using mst with
# a sparse connectivity matrix
X = np.array([[0, 0, 0], [0, 0, 0], [1, 1, 1], [1, 1, 1], [2, 2, 2], [2, 2, 2]])
true_labels = np.array([0, 0, 1, 1, 2, 2])
connectivity = kneighbors_graph(X, n_neighbors=3, include_self=False)
connectivity = 0.5 * (connectivity + connectivity.T)
connectivity, n_components = _fix_connectivity(X, connectivity, "euclidean")
for linkage in ("single", "average", "average", "ward"):
clustering = AgglomerativeClustering(
n_clusters=3, linkage=linkage, connectivity=connectivity
)
clustering.fit(X)
assert_almost_equal(
normalized_mutual_info_score(clustering.labels_, true_labels), 1
)
def test_connectivity_propagation():
# Check that connectivity in the ward tree is propagated correctly during
# merging.
X = np.array(
[
(0.014, 0.120),
(0.014, 0.099),
(0.014, 0.097),
(0.017, 0.153),
(0.017, 0.153),
(0.018, 0.153),
(0.018, 0.153),
(0.018, 0.153),
(0.018, 0.153),
(0.018, 0.153),
(0.018, 0.153),
(0.018, 0.153),
(0.018, 0.152),
(0.018, 0.149),
(0.018, 0.144),
]
)
connectivity = kneighbors_graph(X, 10, include_self=False)
ward = AgglomerativeClustering(
n_clusters=4, connectivity=connectivity, linkage="ward"
)
# If changes are not propagated correctly, fit crashes with an
# IndexError
ward.fit(X)
def test_ward_tree_children_order(global_random_seed):
# Check that children are ordered in the same way for both structured and
# unstructured versions of ward_tree.
# test on five random datasets
n, p = 10, 5
rng = np.random.RandomState(global_random_seed)
connectivity = np.ones((n, n))
for i in range(5):
X = 0.1 * rng.normal(size=(n, p))
X -= 4.0 * np.arange(n)[:, np.newaxis]
X -= X.mean(axis=1)[:, np.newaxis]
out_unstructured = ward_tree(X)
out_structured = ward_tree(X, connectivity=connectivity)
assert_array_equal(out_unstructured[0], out_structured[0])
def test_ward_linkage_tree_return_distance(global_random_seed):
# Test return_distance option on linkage and ward trees
# test that return_distance when set true, gives same
# output on both structured and unstructured clustering.
n, p = 10, 5
rng = np.random.RandomState(global_random_seed)
connectivity = np.ones((n, n))
for i in range(5):
X = 0.1 * rng.normal(size=(n, p))
X -= 4.0 * np.arange(n)[:, np.newaxis]
X -= X.mean(axis=1)[:, np.newaxis]
out_unstructured = ward_tree(X, return_distance=True)
out_structured = ward_tree(X, connectivity=connectivity, return_distance=True)
# get children
children_unstructured = out_unstructured[0]
children_structured = out_structured[0]
# check if we got the same clusters
assert_array_equal(children_unstructured, children_structured)
# check if the distances are the same
dist_unstructured = out_unstructured[-1]
dist_structured = out_structured[-1]
assert_array_almost_equal(dist_unstructured, dist_structured)
for linkage in ["average", "complete", "single"]:
structured_items = linkage_tree(
X, connectivity=connectivity, linkage=linkage, return_distance=True
)[-1]
unstructured_items = linkage_tree(X, linkage=linkage, return_distance=True)[
-1
]
structured_dist = structured_items[-1]
unstructured_dist = unstructured_items[-1]
structured_children = structured_items[0]
unstructured_children = unstructured_items[0]
assert_array_almost_equal(structured_dist, unstructured_dist)
assert_array_almost_equal(structured_children, unstructured_children)
# test on the following dataset where we know the truth
# taken from scipy/cluster/tests/hierarchy_test_data.py
X = np.array(
[
[1.43054825, -7.5693489],
[6.95887839, 6.82293382],
[2.87137846, -9.68248579],
[7.87974764, -6.05485803],
[8.24018364, -6.09495602],
[7.39020262, 8.54004355],
]
)
# truth
linkage_X_ward = np.array(
[
[3.0, 4.0, 0.36265956, 2.0],
[1.0, 5.0, 1.77045373, 2.0],
[0.0, 2.0, 2.55760419, 2.0],
[6.0, 8.0, 9.10208346, 4.0],
[7.0, 9.0, 24.7784379, 6.0],
]
)
linkage_X_complete = np.array(
[
[3.0, 4.0, 0.36265956, 2.0],
[1.0, 5.0, 1.77045373, 2.0],
[0.0, 2.0, 2.55760419, 2.0],
[6.0, 8.0, 6.96742194, 4.0],
[7.0, 9.0, 18.77445997, 6.0],
]
)
linkage_X_average = np.array(
[
[3.0, 4.0, 0.36265956, 2.0],
[1.0, 5.0, 1.77045373, 2.0],
[0.0, 2.0, 2.55760419, 2.0],
[6.0, 8.0, 6.55832839, 4.0],
[7.0, 9.0, 15.44089605, 6.0],
]
)
n_samples, n_features = np.shape(X)
connectivity_X = np.ones((n_samples, n_samples))
out_X_unstructured = ward_tree(X, return_distance=True)
out_X_structured = ward_tree(X, connectivity=connectivity_X, return_distance=True)
# check that the labels are the same
assert_array_equal(linkage_X_ward[:, :2], out_X_unstructured[0])
assert_array_equal(linkage_X_ward[:, :2], out_X_structured[0])
# check that the distances are correct
assert_array_almost_equal(linkage_X_ward[:, 2], out_X_unstructured[4])
assert_array_almost_equal(linkage_X_ward[:, 2], out_X_structured[4])
linkage_options = ["complete", "average", "single"]
X_linkage_truth = [linkage_X_complete, linkage_X_average]
for linkage, X_truth in zip(linkage_options, X_linkage_truth):
out_X_unstructured = linkage_tree(X, return_distance=True, linkage=linkage)
out_X_structured = linkage_tree(
X, connectivity=connectivity_X, linkage=linkage, return_distance=True
)
# check that the labels are the same
assert_array_equal(X_truth[:, :2], out_X_unstructured[0])
assert_array_equal(X_truth[:, :2], out_X_structured[0])
# check that the distances are correct
assert_array_almost_equal(X_truth[:, 2], out_X_unstructured[4])
assert_array_almost_equal(X_truth[:, 2], out_X_structured[4])
def test_connectivity_fixing_non_lil():
# Check non regression of a bug if a non item assignable connectivity is
# provided with more than one component.
# create dummy data
x = np.array([[0, 0], [1, 1]])
# create a mask with several components to force connectivity fixing
m = np.array([[True, False], [False, True]])
c = grid_to_graph(n_x=2, n_y=2, mask=m)
w = AgglomerativeClustering(connectivity=c, linkage="ward")
with pytest.warns(UserWarning):
w.fit(x)
def test_int_float_dict():
rng = np.random.RandomState(0)
keys = np.unique(rng.randint(100, size=10).astype(np.intp, copy=False))
values = rng.rand(len(keys))
d = IntFloatDict(keys, values)
for key, value in zip(keys, values):
assert d[key] == value
other_keys = np.arange(50, dtype=np.intp)[::2]
other_values = np.full(50, 0.5)[::2]
other = IntFloatDict(other_keys, other_values)
# Complete smoke test
max_merge(d, other, mask=np.ones(100, dtype=np.intp), n_a=1, n_b=1)
average_merge(d, other, mask=np.ones(100, dtype=np.intp), n_a=1, n_b=1)
def test_connectivity_callable():
rng = np.random.RandomState(0)
X = rng.rand(20, 5)
connectivity = kneighbors_graph(X, 3, include_self=False)
aglc1 = AgglomerativeClustering(connectivity=connectivity)
aglc2 = AgglomerativeClustering(
connectivity=partial(kneighbors_graph, n_neighbors=3, include_self=False)
)
aglc1.fit(X)
aglc2.fit(X)
assert_array_equal(aglc1.labels_, aglc2.labels_)
def test_connectivity_ignores_diagonal():
rng = np.random.RandomState(0)
X = rng.rand(20, 5)
connectivity = kneighbors_graph(X, 3, include_self=False)
connectivity_include_self = kneighbors_graph(X, 3, include_self=True)
aglc1 = AgglomerativeClustering(connectivity=connectivity)
aglc2 = AgglomerativeClustering(connectivity=connectivity_include_self)
aglc1.fit(X)
aglc2.fit(X)
assert_array_equal(aglc1.labels_, aglc2.labels_)
def test_compute_full_tree():
# Test that the full tree is computed if n_clusters is small
rng = np.random.RandomState(0)
X = rng.randn(10, 2)
connectivity = kneighbors_graph(X, 5, include_self=False)
# When n_clusters is less, the full tree should be built
# that is the number of merges should be n_samples - 1
agc = AgglomerativeClustering(n_clusters=2, connectivity=connectivity)
agc.fit(X)
n_samples = X.shape[0]
n_nodes = agc.children_.shape[0]
assert n_nodes == n_samples - 1
# When n_clusters is large, greater than max of 100 and 0.02 * n_samples.
# we should stop when there are n_clusters.
n_clusters = 101
X = rng.randn(200, 2)
connectivity = kneighbors_graph(X, 10, include_self=False)
agc = AgglomerativeClustering(n_clusters=n_clusters, connectivity=connectivity)
agc.fit(X)
n_samples = X.shape[0]
n_nodes = agc.children_.shape[0]
assert n_nodes == n_samples - n_clusters
def test_n_components():
# Test n_components returned by linkage, average and ward tree
rng = np.random.RandomState(0)
X = rng.rand(5, 5)
# Connectivity matrix having five components.
connectivity = np.eye(5)
for linkage_func in _TREE_BUILDERS.values():
assert ignore_warnings(linkage_func)(X, connectivity=connectivity)[1] == 5
def test_affinity_passed_to_fix_connectivity():
# Test that the affinity parameter is actually passed to the pairwise
# function
size = 2
rng = np.random.RandomState(0)
X = rng.randn(size, size)
mask = np.array([True, False, False, True])
connectivity = grid_to_graph(n_x=size, n_y=size, mask=mask, return_as=np.ndarray)
class FakeAffinity:
def __init__(self):
self.counter = 0
def increment(self, *args, **kwargs):
self.counter += 1
return self.counter
fa = FakeAffinity()
linkage_tree(X, connectivity=connectivity, affinity=fa.increment)
assert fa.counter == 3
@pytest.mark.parametrize("linkage", ["ward", "complete", "average"])
def test_agglomerative_clustering_with_distance_threshold(linkage, global_random_seed):
# Check that we obtain the correct number of clusters with
# agglomerative clustering with distance_threshold.
rng = np.random.RandomState(global_random_seed)
mask = np.ones([10, 10], dtype=bool)
n_samples = 100
X = rng.randn(n_samples, 50)
connectivity = grid_to_graph(*mask.shape)
# test when distance threshold is set to 10
distance_threshold = 10
for conn in [None, connectivity]:
clustering = AgglomerativeClustering(
n_clusters=None,
distance_threshold=distance_threshold,
connectivity=conn,
linkage=linkage,
)
clustering.fit(X)
clusters_produced = clustering.labels_
num_clusters_produced = len(np.unique(clustering.labels_))
# test if the clusters produced match the point in the linkage tree
# where the distance exceeds the threshold
tree_builder = _TREE_BUILDERS[linkage]
children, n_components, n_leaves, parent, distances = tree_builder(
X, connectivity=conn, n_clusters=None, return_distance=True
)
num_clusters_at_threshold = (
np.count_nonzero(distances >= distance_threshold) + 1
)
# test number of clusters produced
assert num_clusters_at_threshold == num_clusters_produced
# test clusters produced
clusters_at_threshold = _hc_cut(
n_clusters=num_clusters_produced, children=children, n_leaves=n_leaves
)
assert np.array_equiv(clusters_produced, clusters_at_threshold)
def test_small_distance_threshold(global_random_seed):
rng = np.random.RandomState(global_random_seed)
n_samples = 10
X = rng.randint(-300, 300, size=(n_samples, 3))
# this should result in all data in their own clusters, given that
# their pairwise distances are bigger than .1 (which may not be the case
# with a different random seed).
clustering = AgglomerativeClustering(
n_clusters=None, distance_threshold=1.0, linkage="single"
).fit(X)
# check that the pairwise distances are indeed all larger than .1
all_distances = pairwise_distances(X, metric="minkowski", p=2)
np.fill_diagonal(all_distances, np.inf)
assert np.all(all_distances > 0.1)
assert clustering.n_clusters_ == n_samples
def test_cluster_distances_with_distance_threshold(global_random_seed):
rng = np.random.RandomState(global_random_seed)
n_samples = 100
X = rng.randint(-10, 10, size=(n_samples, 3))
# check the distances within the clusters and with other clusters
distance_threshold = 4
clustering = AgglomerativeClustering(
n_clusters=None, distance_threshold=distance_threshold, linkage="single"
).fit(X)
labels = clustering.labels_
D = pairwise_distances(X, metric="minkowski", p=2)
# to avoid taking the 0 diagonal in min()
np.fill_diagonal(D, np.inf)
for label in np.unique(labels):
in_cluster_mask = labels == label
max_in_cluster_distance = (
D[in_cluster_mask][:, in_cluster_mask].min(axis=0).max()
)
min_out_cluster_distance = (
D[in_cluster_mask][:, ~in_cluster_mask].min(axis=0).min()
)
# single data point clusters only have that inf diagonal here
if in_cluster_mask.sum() > 1:
assert max_in_cluster_distance < distance_threshold
assert min_out_cluster_distance >= distance_threshold
@pytest.mark.parametrize("linkage", ["ward", "complete", "average"])
@pytest.mark.parametrize(
("threshold", "y_true"), [(0.5, [1, 0]), (1.0, [1, 0]), (1.5, [0, 0])]
)
def test_agglomerative_clustering_with_distance_threshold_edge_case(
linkage, threshold, y_true
):
# test boundary case of distance_threshold matching the distance
X = [[0], [1]]
clusterer = AgglomerativeClustering(
n_clusters=None, distance_threshold=threshold, linkage=linkage
)
y_pred = clusterer.fit_predict(X)
assert adjusted_rand_score(y_true, y_pred) == 1
def test_dist_threshold_invalid_parameters():
X = [[0], [1]]
with pytest.raises(ValueError, match="Exactly one of "):
AgglomerativeClustering(n_clusters=None, distance_threshold=None).fit(X)
with pytest.raises(ValueError, match="Exactly one of "):
AgglomerativeClustering(n_clusters=2, distance_threshold=1).fit(X)
X = [[0], [1]]
with pytest.raises(ValueError, match="compute_full_tree must be True if"):
AgglomerativeClustering(
n_clusters=None, distance_threshold=1, compute_full_tree=False
).fit(X)
def test_invalid_shape_precomputed_dist_matrix():
# Check that an error is raised when affinity='precomputed'
# and a non square matrix is passed (PR #16257).
rng = np.random.RandomState(0)
X = rng.rand(5, 3)
with pytest.raises(
ValueError,
match=r"Distance matrix should be square, got matrix of shape \(5, 3\)",
):
AgglomerativeClustering(metric="precomputed", linkage="complete").fit(X)
def test_precomputed_connectivity_metric_with_2_connected_components():
"""Check that connecting components works when connectivity and
affinity are both precomputed and the number of connected components is
greater than 1. Non-regression test for #16151.
"""
connectivity_matrix = np.array(
[
[0, 1, 1, 0, 0],
[0, 0, 1, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 1],
[0, 0, 0, 0, 0],
]
)
# ensure that connectivity_matrix has two connected components
assert connected_components(connectivity_matrix)[0] == 2
rng = np.random.RandomState(0)
X = rng.randn(5, 10)
X_dist = pairwise_distances(X)
clusterer_precomputed = AgglomerativeClustering(
metric="precomputed", connectivity=connectivity_matrix, linkage="complete"
)
msg = "Completing it to avoid stopping the tree early"
with pytest.warns(UserWarning, match=msg):
clusterer_precomputed.fit(X_dist)
clusterer = AgglomerativeClustering(
connectivity=connectivity_matrix, linkage="complete"
)
with pytest.warns(UserWarning, match=msg):
clusterer.fit(X)
assert_array_equal(clusterer.labels_, clusterer_precomputed.labels_)
assert_array_equal(clusterer.children_, clusterer_precomputed.children_)

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"""
Testing for mean shift clustering methods
"""
import warnings
import numpy as np
import pytest
from sklearn.cluster import MeanShift, estimate_bandwidth, get_bin_seeds, mean_shift
from sklearn.datasets import make_blobs
from sklearn.metrics import v_measure_score
from sklearn.utils._testing import assert_allclose, assert_array_equal
n_clusters = 3
centers = np.array([[1, 1], [-1, -1], [1, -1]]) + 10
X, _ = make_blobs(
n_samples=300,
n_features=2,
centers=centers,
cluster_std=0.4,
shuffle=True,
random_state=11,
)
def test_convergence_of_1d_constant_data():
# Test convergence using 1D constant data
# Non-regression test for:
# https://github.com/scikit-learn/scikit-learn/issues/28926
model = MeanShift()
n_iter = model.fit(np.ones(10).reshape(-1, 1)).n_iter_
assert n_iter < model.max_iter
def test_estimate_bandwidth():
# Test estimate_bandwidth
bandwidth = estimate_bandwidth(X, n_samples=200)
assert 0.9 <= bandwidth <= 1.5
def test_estimate_bandwidth_1sample(global_dtype):
# Test estimate_bandwidth when n_samples=1 and quantile<1, so that
# n_neighbors is set to 1.
bandwidth = estimate_bandwidth(
X.astype(global_dtype, copy=False), n_samples=1, quantile=0.3
)
assert bandwidth.dtype == X.dtype
assert bandwidth == pytest.approx(0.0, abs=1e-5)
@pytest.mark.parametrize(
"bandwidth, cluster_all, expected, first_cluster_label",
[(1.2, True, 3, 0), (1.2, False, 4, -1)],
)
def test_mean_shift(
global_dtype, bandwidth, cluster_all, expected, first_cluster_label
):
# Test MeanShift algorithm
X_with_global_dtype = X.astype(global_dtype, copy=False)
ms = MeanShift(bandwidth=bandwidth, cluster_all=cluster_all)
labels = ms.fit(X_with_global_dtype).labels_
labels_unique = np.unique(labels)
n_clusters_ = len(labels_unique)
assert n_clusters_ == expected
assert labels_unique[0] == first_cluster_label
assert ms.cluster_centers_.dtype == global_dtype
cluster_centers, labels_mean_shift = mean_shift(
X_with_global_dtype, cluster_all=cluster_all
)
labels_mean_shift_unique = np.unique(labels_mean_shift)
n_clusters_mean_shift = len(labels_mean_shift_unique)
assert n_clusters_mean_shift == expected
assert labels_mean_shift_unique[0] == first_cluster_label
assert cluster_centers.dtype == global_dtype
# TODO: remove mark once loky bug is fixed:
# https://github.com/joblib/loky/issues/458
@pytest.mark.thread_unsafe
def test_parallel(global_dtype, global_random_seed):
centers = np.array([[1, 1], [-1, -1], [1, -1]]) + 10
X, _ = make_blobs(
n_samples=50,
n_features=2,
centers=centers,
cluster_std=0.4,
shuffle=True,
random_state=global_random_seed,
)
X = X.astype(global_dtype, copy=False)
ms1 = MeanShift(n_jobs=2)
ms1.fit(X)
ms2 = MeanShift()
ms2.fit(X)
assert_allclose(ms1.cluster_centers_, ms2.cluster_centers_)
assert ms1.cluster_centers_.dtype == ms2.cluster_centers_.dtype
assert_array_equal(ms1.labels_, ms2.labels_)
def test_meanshift_predict(global_dtype):
# Test MeanShift.predict
ms = MeanShift(bandwidth=1.2)
X_with_global_dtype = X.astype(global_dtype, copy=False)
labels = ms.fit_predict(X_with_global_dtype)
labels2 = ms.predict(X_with_global_dtype)
assert_array_equal(labels, labels2)
def test_meanshift_all_orphans():
# init away from the data, crash with a sensible warning
ms = MeanShift(bandwidth=0.1, seeds=[[-9, -9], [-10, -10]])
msg = "No point was within bandwidth=0.1"
with pytest.raises(ValueError, match=msg):
ms.fit(
X,
)
def test_unfitted():
# Non-regression: before fit, there should be not fitted attributes.
ms = MeanShift()
assert not hasattr(ms, "cluster_centers_")
assert not hasattr(ms, "labels_")
def test_cluster_intensity_tie(global_dtype):
X = np.array([[1, 1], [2, 1], [1, 0], [4, 7], [3, 5], [3, 6]], dtype=global_dtype)
c1 = MeanShift(bandwidth=2).fit(X)
X = np.array([[4, 7], [3, 5], [3, 6], [1, 1], [2, 1], [1, 0]], dtype=global_dtype)
c2 = MeanShift(bandwidth=2).fit(X)
assert_array_equal(c1.labels_, [1, 1, 1, 0, 0, 0])
assert_array_equal(c2.labels_, [0, 0, 0, 1, 1, 1])
def test_bin_seeds(global_dtype):
# Test the bin seeding technique which can be used in the mean shift
# algorithm
# Data is just 6 points in the plane
X = np.array(
[[1.0, 1.0], [1.4, 1.4], [1.8, 1.2], [2.0, 1.0], [2.1, 1.1], [0.0, 0.0]],
dtype=global_dtype,
)
# With a bin coarseness of 1.0 and min_bin_freq of 1, 3 bins should be
# found
ground_truth = {(1.0, 1.0), (2.0, 1.0), (0.0, 0.0)}
test_bins = get_bin_seeds(X, 1, 1)
test_result = set(tuple(p) for p in test_bins)
assert len(ground_truth.symmetric_difference(test_result)) == 0
# With a bin coarseness of 1.0 and min_bin_freq of 2, 2 bins should be
# found
ground_truth = {(1.0, 1.0), (2.0, 1.0)}
test_bins = get_bin_seeds(X, 1, 2)
test_result = set(tuple(p) for p in test_bins)
assert len(ground_truth.symmetric_difference(test_result)) == 0
# With a bin size of 0.01 and min_bin_freq of 1, 6 bins should be found
# we bail and use the whole data here.
with warnings.catch_warnings(record=True):
test_bins = get_bin_seeds(X, 0.01, 1)
assert_allclose(test_bins, X)
# tight clusters around [0, 0] and [1, 1], only get two bins
X, _ = make_blobs(
n_samples=100,
n_features=2,
centers=[[0, 0], [1, 1]],
cluster_std=0.1,
random_state=0,
)
X = X.astype(global_dtype, copy=False)
test_bins = get_bin_seeds(X, 1)
assert_array_equal(test_bins, [[0, 0], [1, 1]])
@pytest.mark.parametrize("max_iter", [1, 100])
def test_max_iter(max_iter):
clusters1, _ = mean_shift(X, max_iter=max_iter)
ms = MeanShift(max_iter=max_iter).fit(X)
clusters2 = ms.cluster_centers_
assert ms.n_iter_ <= ms.max_iter
assert len(clusters1) == len(clusters2)
for c1, c2 in zip(clusters1, clusters2):
assert np.allclose(c1, c2)
def test_mean_shift_zero_bandwidth(global_dtype):
# Check that mean shift works when the estimated bandwidth is 0.
X = np.array([1, 1, 1, 2, 2, 2, 3, 3], dtype=global_dtype).reshape(-1, 1)
# estimate_bandwidth with default args returns 0 on this dataset
bandwidth = estimate_bandwidth(X)
assert bandwidth == 0
# get_bin_seeds with a 0 bin_size should return the dataset itself
assert get_bin_seeds(X, bin_size=bandwidth) is X
# MeanShift with binning and a 0 estimated bandwidth should be equivalent
# to no binning.
ms_binning = MeanShift(bin_seeding=True, bandwidth=None).fit(X)
ms_nobinning = MeanShift(bin_seeding=False).fit(X)
expected_labels = np.array([0, 0, 0, 1, 1, 1, 2, 2])
assert v_measure_score(ms_binning.labels_, expected_labels) == pytest.approx(1)
assert v_measure_score(ms_nobinning.labels_, expected_labels) == pytest.approx(1)
assert_allclose(ms_binning.cluster_centers_, ms_nobinning.cluster_centers_)

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# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
import numpy as np
import pytest
from sklearn.cluster import DBSCAN, OPTICS
from sklearn.cluster._optics import _extend_region, _extract_xi_labels
from sklearn.cluster.tests.common import generate_clustered_data
from sklearn.datasets import make_blobs
from sklearn.exceptions import DataConversionWarning, EfficiencyWarning
from sklearn.metrics.cluster import contingency_matrix
from sklearn.metrics.pairwise import pairwise_distances
from sklearn.utils import shuffle
from sklearn.utils._testing import assert_allclose, assert_array_equal
from sklearn.utils.fixes import CSR_CONTAINERS
rng = np.random.RandomState(0)
n_points_per_cluster = 10
C1 = [-5, -2] + 0.8 * rng.randn(n_points_per_cluster, 2)
C2 = [4, -1] + 0.1 * rng.randn(n_points_per_cluster, 2)
C3 = [1, -2] + 0.2 * rng.randn(n_points_per_cluster, 2)
C4 = [-2, 3] + 0.3 * rng.randn(n_points_per_cluster, 2)
C5 = [3, -2] + 1.6 * rng.randn(n_points_per_cluster, 2)
C6 = [5, 6] + 2 * rng.randn(n_points_per_cluster, 2)
X = np.vstack((C1, C2, C3, C4, C5, C6))
@pytest.mark.parametrize(
("r_plot", "end"),
[
[[10, 8.9, 8.8, 8.7, 7, 10], 3],
[[10, 8.9, 8.8, 8.7, 8.6, 7, 10], 0],
[[10, 8.9, 8.8, 8.7, 7, 6, np.inf], 4],
[[10, 8.9, 8.8, 8.7, 7, 6, np.inf], 4],
],
)
def test_extend_downward(r_plot, end):
r_plot = np.array(r_plot)
ratio = r_plot[:-1] / r_plot[1:]
steep_downward = ratio >= 1 / 0.9
upward = ratio < 1
e = _extend_region(steep_downward, upward, 0, 2)
assert e == end
@pytest.mark.parametrize(
("r_plot", "end"),
[
[[1, 2, 2.1, 2.2, 4, 8, 8, np.inf], 6],
[[1, 2, 2.1, 2.2, 2.3, 4, 8, 8, np.inf], 0],
[[1, 2, 2.1, 2, np.inf], 0],
[[1, 2, 2.1, np.inf], 2],
],
)
def test_extend_upward(r_plot, end):
r_plot = np.array(r_plot)
ratio = r_plot[:-1] / r_plot[1:]
steep_upward = ratio <= 0.9
downward = ratio > 1
e = _extend_region(steep_upward, downward, 0, 2)
assert e == end
@pytest.mark.parametrize(
("ordering", "clusters", "expected"),
[
[[0, 1, 2, 3], [[0, 1], [2, 3]], [0, 0, 1, 1]],
[[0, 1, 2, 3], [[0, 1], [3, 3]], [0, 0, -1, 1]],
[[0, 1, 2, 3], [[0, 1], [3, 3], [0, 3]], [0, 0, -1, 1]],
[[3, 1, 2, 0], [[0, 1], [3, 3], [0, 3]], [1, 0, -1, 0]],
],
)
def test_the_extract_xi_labels(ordering, clusters, expected):
labels = _extract_xi_labels(ordering, clusters)
assert_array_equal(labels, expected)
def test_extract_xi(global_dtype):
# small and easy test (no clusters around other clusters)
# but with a clear noise data.
# global_random_seed is not used here since the expected labels
# are hardcoded for these specific data.
rng = np.random.RandomState(0)
n_points_per_cluster = 5
C1 = [-5, -2] + 0.8 * rng.randn(n_points_per_cluster, 2)
C2 = [4, -1] + 0.1 * rng.randn(n_points_per_cluster, 2)
C3 = [1, -2] + 0.2 * rng.randn(n_points_per_cluster, 2)
C4 = [-2, 3] + 0.3 * rng.randn(n_points_per_cluster, 2)
C5 = [3, -2] + 0.6 * rng.randn(n_points_per_cluster, 2)
C6 = [5, 6] + 0.2 * rng.randn(n_points_per_cluster, 2)
X = np.vstack((C1, C2, C3, C4, C5, np.array([[100, 100]]), C6)).astype(
global_dtype, copy=False
)
expected_labels = np.r_[[2] * 5, [0] * 5, [1] * 5, [3] * 5, [1] * 5, -1, [4] * 5]
X, expected_labels = shuffle(X, expected_labels, random_state=rng)
clust = OPTICS(
min_samples=3, min_cluster_size=2, max_eps=20, cluster_method="xi", xi=0.4
).fit(X)
assert_array_equal(clust.labels_, expected_labels)
# check float min_samples and min_cluster_size
clust = OPTICS(
min_samples=0.1, min_cluster_size=0.08, max_eps=20, cluster_method="xi", xi=0.4
).fit(X)
assert_array_equal(clust.labels_, expected_labels)
X = np.vstack((C1, C2, C3, C4, C5, np.array([[100, 100]] * 2), C6)).astype(
global_dtype, copy=False
)
expected_labels = np.r_[
[1] * 5, [3] * 5, [2] * 5, [0] * 5, [2] * 5, -1, -1, [4] * 5
]
X, expected_labels = shuffle(X, expected_labels, random_state=rng)
clust = OPTICS(
min_samples=3, min_cluster_size=3, max_eps=20, cluster_method="xi", xi=0.3
).fit(X)
# this may fail if the predecessor correction is not at work!
assert_array_equal(clust.labels_, expected_labels)
C1 = [[0, 0], [0, 0.1], [0, -0.1], [0.1, 0]]
C2 = [[10, 10], [10, 9], [10, 11], [9, 10]]
C3 = [[100, 100], [100, 90], [100, 110], [90, 100]]
X = np.vstack((C1, C2, C3)).astype(global_dtype, copy=False)
expected_labels = np.r_[[0] * 4, [1] * 4, [2] * 4]
X, expected_labels = shuffle(X, expected_labels, random_state=rng)
clust = OPTICS(
min_samples=2, min_cluster_size=2, max_eps=np.inf, cluster_method="xi", xi=0.04
).fit(X)
assert_array_equal(clust.labels_, expected_labels)
def test_cluster_hierarchy(global_dtype, global_random_seed):
rng = np.random.RandomState(global_random_seed)
n_points_per_cluster = 100
C1 = [0, 0] + 2 * rng.randn(n_points_per_cluster, 2).astype(
global_dtype, copy=False
)
C2 = [0, 0] + 50 * rng.randn(n_points_per_cluster, 2).astype(
global_dtype, copy=False
)
X = np.vstack((C1, C2))
X = shuffle(X, random_state=rng)
clusters = OPTICS(min_samples=20, xi=0.2).fit(X).cluster_hierarchy_
assert clusters.shape == (2, 2)
# The first cluster should contain all point from C1 but due to how the data is
# generated, some points from C2 may end up in it.
assert 100 <= np.diff(clusters[0]) + 1 <= 115
# The second cluster should contain all points from C1 and C2.
assert np.diff(clusters[-1]) + 1 == 200
@pytest.mark.parametrize(
"csr_container, metric",
[(None, "minkowski")] + [(container, "euclidean") for container in CSR_CONTAINERS],
)
def test_correct_number_of_clusters(metric, csr_container):
# in 'auto' mode
n_clusters = 3
X = generate_clustered_data(n_clusters=n_clusters)
# Parameters chosen specifically for this task.
# Compute OPTICS
clust = OPTICS(max_eps=5.0 * 6.0, min_samples=4, xi=0.1, metric=metric)
clust.fit(csr_container(X) if csr_container is not None else X)
# number of clusters, ignoring noise if present
n_clusters_1 = len(set(clust.labels_)) - int(-1 in clust.labels_)
assert n_clusters_1 == n_clusters
# check attribute types and sizes
assert clust.labels_.shape == (len(X),)
assert clust.labels_.dtype.kind == "i"
assert clust.reachability_.shape == (len(X),)
assert clust.reachability_.dtype.kind == "f"
assert clust.core_distances_.shape == (len(X),)
assert clust.core_distances_.dtype.kind == "f"
assert clust.ordering_.shape == (len(X),)
assert clust.ordering_.dtype.kind == "i"
assert set(clust.ordering_) == set(range(len(X)))
def test_minimum_number_of_sample_check():
# test that we check a minimum number of samples
msg = "min_samples must be no greater than"
# Compute OPTICS
X = [[1, 1]]
clust = OPTICS(max_eps=5.0 * 0.3, min_samples=10, min_cluster_size=1.0)
# Run the fit
with pytest.raises(ValueError, match=msg):
clust.fit(X)
def test_bad_extract():
# Test an extraction of eps too close to original eps
msg = "Specify an epsilon smaller than 0.15. Got 0.3."
centers = [[1, 1], [-1, -1], [1, -1]]
X, labels_true = make_blobs(
n_samples=750, centers=centers, cluster_std=0.4, random_state=0
)
# Compute OPTICS
clust = OPTICS(max_eps=5.0 * 0.03, cluster_method="dbscan", eps=0.3, min_samples=10)
with pytest.raises(ValueError, match=msg):
clust.fit(X)
def test_bad_reachability():
msg = "All reachability values are inf. Set a larger max_eps."
centers = [[1, 1], [-1, -1], [1, -1]]
X, labels_true = make_blobs(
n_samples=750, centers=centers, cluster_std=0.4, random_state=0
)
with pytest.warns(UserWarning, match=msg):
clust = OPTICS(max_eps=5.0 * 0.003, min_samples=10, eps=0.015)
clust.fit(X)
def test_nowarn_if_metric_bool_data_bool():
# make sure no warning is raised if metric and data are both boolean
# non-regression test for
# https://github.com/scikit-learn/scikit-learn/issues/18996
pairwise_metric = "rogerstanimoto"
X = np.random.randint(2, size=(5, 2), dtype=bool)
with warnings.catch_warnings():
warnings.simplefilter("error", DataConversionWarning)
OPTICS(metric=pairwise_metric).fit(X)
def test_warn_if_metric_bool_data_no_bool():
# make sure a *single* conversion warning is raised if metric is boolean
# but data isn't
# non-regression test for
# https://github.com/scikit-learn/scikit-learn/issues/18996
pairwise_metric = "rogerstanimoto"
X = np.random.randint(2, size=(5, 2), dtype=np.int32)
msg = f"Data will be converted to boolean for metric {pairwise_metric}"
with pytest.warns(DataConversionWarning, match=msg) as warn_record:
# Silence a DeprecationWarning from joblib <= 1.5.1 in Python 3.14+.
warnings.filterwarnings(
"ignore",
message="'asyncio.iscoroutinefunction' is deprecated",
category=DeprecationWarning,
)
OPTICS(metric=pairwise_metric).fit(X)
assert len(warn_record) == 1
def test_nowarn_if_metric_no_bool():
# make sure no conversion warning is raised if
# metric isn't boolean, no matter what the data type is
pairwise_metric = "minkowski"
X_bool = np.random.randint(2, size=(5, 2), dtype=bool)
X_num = np.random.randint(2, size=(5, 2), dtype=np.int32)
with warnings.catch_warnings():
warnings.simplefilter("error", DataConversionWarning)
# fit boolean data
OPTICS(metric=pairwise_metric).fit(X_bool)
# fit numeric data
OPTICS(metric=pairwise_metric).fit(X_num)
def test_close_extract():
# Test extract where extraction eps is close to scaled max_eps
centers = [[1, 1], [-1, -1], [1, -1]]
X, labels_true = make_blobs(
n_samples=750, centers=centers, cluster_std=0.4, random_state=0
)
# Compute OPTICS
clust = OPTICS(max_eps=1.0, cluster_method="dbscan", eps=0.3, min_samples=10).fit(X)
# Cluster ordering starts at 0; max cluster label = 2 is 3 clusters
assert max(clust.labels_) == 2
@pytest.mark.parametrize("eps", [0.1, 0.3, 0.5])
@pytest.mark.parametrize("min_samples", [3, 10, 20])
@pytest.mark.parametrize(
"csr_container, metric",
[(None, "minkowski"), (None, "euclidean")]
+ [(container, "euclidean") for container in CSR_CONTAINERS],
)
def test_dbscan_optics_parity(eps, min_samples, metric, global_dtype, csr_container):
# Test that OPTICS clustering labels are <= 5% difference of DBSCAN
centers = [[1, 1], [-1, -1], [1, -1]]
X, labels_true = make_blobs(
n_samples=150, centers=centers, cluster_std=0.4, random_state=0
)
X = csr_container(X) if csr_container is not None else X
X = X.astype(global_dtype, copy=False)
# calculate optics with dbscan extract at 0.3 epsilon
op = OPTICS(
min_samples=min_samples, cluster_method="dbscan", eps=eps, metric=metric
).fit(X)
# calculate dbscan labels
db = DBSCAN(eps=eps, min_samples=min_samples).fit(X)
contingency = contingency_matrix(db.labels_, op.labels_)
agree = min(
np.sum(np.max(contingency, axis=0)), np.sum(np.max(contingency, axis=1))
)
disagree = X.shape[0] - agree
percent_mismatch = np.round((disagree - 1) / X.shape[0], 2)
# verify label mismatch is <= 5% labels
assert percent_mismatch <= 0.05
def test_min_samples_edge_case(global_dtype):
C1 = [[0, 0], [0, 0.1], [0, -0.1]]
C2 = [[10, 10], [10, 9], [10, 11]]
C3 = [[100, 100], [100, 96], [100, 106]]
X = np.vstack((C1, C2, C3)).astype(global_dtype, copy=False)
expected_labels = np.r_[[0] * 3, [1] * 3, [2] * 3]
clust = OPTICS(min_samples=3, max_eps=7, cluster_method="xi", xi=0.04).fit(X)
assert_array_equal(clust.labels_, expected_labels)
expected_labels = np.r_[[0] * 3, [1] * 3, [-1] * 3]
clust = OPTICS(min_samples=3, max_eps=3, cluster_method="xi", xi=0.04).fit(X)
assert_array_equal(clust.labels_, expected_labels)
expected_labels = np.r_[[-1] * 9]
with pytest.warns(UserWarning, match="All reachability values"):
clust = OPTICS(min_samples=4, max_eps=3, cluster_method="xi", xi=0.04).fit(X)
assert_array_equal(clust.labels_, expected_labels)
# try arbitrary minimum sizes
@pytest.mark.parametrize("min_cluster_size", range(2, X.shape[0] // 10, 23))
def test_min_cluster_size(min_cluster_size, global_dtype):
redX = X[::2].astype(global_dtype, copy=False) # reduce for speed
clust = OPTICS(min_samples=9, min_cluster_size=min_cluster_size).fit(redX)
cluster_sizes = np.bincount(clust.labels_[clust.labels_ != -1])
if cluster_sizes.size:
assert min(cluster_sizes) >= min_cluster_size
# check behaviour is the same when min_cluster_size is a fraction
clust_frac = OPTICS(
min_samples=9,
min_cluster_size=min_cluster_size / redX.shape[0],
)
clust_frac.fit(redX)
assert_array_equal(clust.labels_, clust_frac.labels_)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_min_cluster_size_invalid2(csr_container):
clust = OPTICS(min_cluster_size=len(X) + 1)
with pytest.raises(ValueError, match="must be no greater than the "):
clust.fit(X)
clust = OPTICS(min_cluster_size=len(X) + 1, metric="euclidean")
with pytest.raises(ValueError, match="must be no greater than the "):
clust.fit(csr_container(X))
def test_processing_order():
# Ensure that we consider all unprocessed points,
# not only direct neighbors. when picking the next point.
Y = [[0], [10], [-10], [25]]
clust = OPTICS(min_samples=3, max_eps=15).fit(Y)
assert_array_equal(clust.reachability_, [np.inf, 10, 10, 15])
assert_array_equal(clust.core_distances_, [10, 15, np.inf, np.inf])
assert_array_equal(clust.ordering_, [0, 1, 2, 3])
def test_compare_to_ELKI():
# Expected values, computed with (future) ELKI 0.7.5 using:
# java -jar elki.jar cli -dbc.in csv -dbc.filter FixedDBIDsFilter
# -algorithm clustering.optics.OPTICSHeap -optics.minpts 5
# where the FixedDBIDsFilter gives 0-indexed ids.
r1 = [
np.inf,
1.0574896366427478,
0.7587934993548423,
0.7290174038973836,
0.7290174038973836,
0.7290174038973836,
0.6861627576116127,
0.7587934993548423,
0.9280118450166668,
1.1748022534146194,
3.3355455741292257,
0.49618389254482587,
0.2552805046961355,
0.2552805046961355,
0.24944622248445714,
0.24944622248445714,
0.24944622248445714,
0.2552805046961355,
0.2552805046961355,
0.3086779122185853,
4.163024452756142,
1.623152630340929,
0.45315840475822655,
0.25468325192031926,
0.2254004358159971,
0.18765711877083036,
0.1821471333893275,
0.1821471333893275,
0.18765711877083036,
0.18765711877083036,
0.2240202988740153,
1.154337614548715,
1.342604473837069,
1.323308536402633,
0.8607514948648837,
0.27219111215810565,
0.13260875220533205,
0.13260875220533205,
0.09890587675958984,
0.09890587675958984,
0.13548790801634494,
0.1575483940837384,
0.17515137170530226,
0.17575920159442388,
0.27219111215810565,
0.6101447895405373,
1.3189208094864302,
1.323308536402633,
2.2509184159764577,
2.4517810628594527,
3.675977064404973,
3.8264795626020365,
2.9130735341510614,
2.9130735341510614,
2.9130735341510614,
2.9130735341510614,
2.8459300127258036,
2.8459300127258036,
2.8459300127258036,
3.0321982337972537,
]
o1 = [
0,
3,
6,
4,
7,
8,
2,
9,
5,
1,
31,
30,
32,
34,
33,
38,
39,
35,
37,
36,
44,
21,
23,
24,
22,
25,
27,
29,
26,
28,
20,
40,
45,
46,
10,
15,
11,
13,
17,
19,
18,
12,
16,
14,
47,
49,
43,
48,
42,
41,
53,
57,
51,
52,
56,
59,
54,
55,
58,
50,
]
p1 = [
-1,
0,
3,
6,
6,
6,
8,
3,
7,
5,
1,
31,
30,
30,
34,
34,
34,
32,
32,
37,
36,
44,
21,
23,
24,
22,
25,
25,
22,
22,
22,
21,
40,
45,
46,
10,
15,
15,
13,
13,
15,
11,
19,
15,
10,
47,
12,
45,
14,
43,
42,
53,
57,
57,
57,
57,
59,
59,
59,
58,
]
# Tests against known extraction array
# Does NOT work with metric='euclidean', because sklearn euclidean has
# worse numeric precision. 'minkowski' is slower but more accurate.
clust1 = OPTICS(min_samples=5).fit(X)
assert_array_equal(clust1.ordering_, np.array(o1))
assert_array_equal(clust1.predecessor_[clust1.ordering_], np.array(p1))
assert_allclose(clust1.reachability_[clust1.ordering_], np.array(r1))
# ELKI currently does not print the core distances (which are not used much
# in literature, but we can at least ensure to have this consistency:
for i in clust1.ordering_[1:]:
assert clust1.reachability_[i] >= clust1.core_distances_[clust1.predecessor_[i]]
# Expected values, computed with (future) ELKI 0.7.5 using
r2 = [
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
0.27219111215810565,
0.13260875220533205,
0.13260875220533205,
0.09890587675958984,
0.09890587675958984,
0.13548790801634494,
0.1575483940837384,
0.17515137170530226,
0.17575920159442388,
0.27219111215810565,
0.4928068613197889,
np.inf,
0.2666183922512113,
0.18765711877083036,
0.1821471333893275,
0.1821471333893275,
0.1821471333893275,
0.18715928772277457,
0.18765711877083036,
0.18765711877083036,
0.25468325192031926,
np.inf,
0.2552805046961355,
0.2552805046961355,
0.24944622248445714,
0.24944622248445714,
0.24944622248445714,
0.2552805046961355,
0.2552805046961355,
0.3086779122185853,
0.34466409325984865,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
np.inf,
]
o2 = [
0,
1,
2,
3,
4,
5,
6,
7,
8,
9,
10,
15,
11,
13,
17,
19,
18,
12,
16,
14,
47,
46,
20,
22,
25,
23,
27,
29,
24,
26,
28,
21,
30,
32,
34,
33,
38,
39,
35,
37,
36,
31,
40,
41,
42,
43,
44,
45,
48,
49,
50,
51,
52,
53,
54,
55,
56,
57,
58,
59,
]
p2 = [
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
10,
15,
15,
13,
13,
15,
11,
19,
15,
10,
47,
-1,
20,
22,
25,
25,
25,
25,
22,
22,
23,
-1,
30,
30,
34,
34,
34,
32,
32,
37,
38,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
]
clust2 = OPTICS(min_samples=5, max_eps=0.5).fit(X)
assert_array_equal(clust2.ordering_, np.array(o2))
assert_array_equal(clust2.predecessor_[clust2.ordering_], np.array(p2))
assert_allclose(clust2.reachability_[clust2.ordering_], np.array(r2))
index = np.where(clust1.core_distances_ <= 0.5)[0]
assert_allclose(clust1.core_distances_[index], clust2.core_distances_[index])
def test_extract_dbscan(global_dtype, global_random_seed):
# testing an easy dbscan case. Not including clusters with different
# densities.
rng = np.random.RandomState(global_random_seed)
n_points_per_cluster = 20
C1 = [-5, -2] + 0.2 * rng.randn(n_points_per_cluster, 2)
C2 = [4, -1] + 0.2 * rng.randn(n_points_per_cluster, 2)
C3 = [1, 2] + 0.2 * rng.randn(n_points_per_cluster, 2)
C4 = [-2, 3] + 0.2 * rng.randn(n_points_per_cluster, 2)
X = np.vstack((C1, C2, C3, C4)).astype(global_dtype, copy=False)
clust = OPTICS(cluster_method="dbscan", eps=0.5).fit(X)
assert_array_equal(
np.sort(np.unique(clust.labels_[clust.labels_ != -1])), [0, 1, 2, 3]
)
@pytest.mark.parametrize("csr_container", [None] + CSR_CONTAINERS)
def test_precomputed_dists(global_dtype, csr_container):
redX = X[::2].astype(global_dtype, copy=False)
dists = pairwise_distances(redX, metric="euclidean")
dists = csr_container(dists) if csr_container is not None else dists
with warnings.catch_warnings():
warnings.simplefilter("ignore", EfficiencyWarning)
clust1 = OPTICS(min_samples=10, algorithm="brute", metric="precomputed").fit(
dists
)
clust2 = OPTICS(min_samples=10, algorithm="brute", metric="euclidean").fit(redX)
assert_allclose(clust1.reachability_, clust2.reachability_)
assert_array_equal(clust1.labels_, clust2.labels_)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_optics_input_not_modified_precomputed_sparse_nodiag(
csr_container, global_random_seed
):
"""Check that we don't modify in-place the pre-computed sparse matrix.
Non-regression test for:
https://github.com/scikit-learn/scikit-learn/issues/27508
"""
X = np.random.RandomState(global_random_seed).rand(6, 6)
# Add zeros on the diagonal that will be implicit when creating
# the sparse matrix. If `X` is modified in-place, the zeros from
# the diagonal will be made explicit.
np.fill_diagonal(X, 0)
X = csr_container(X)
assert all(row != col for row, col in zip(*X.nonzero()))
X_copy = X.copy()
OPTICS(metric="precomputed").fit(X)
# Make sure that we did not modify `X` in-place even by creating
# explicit 0s values.
assert X.nnz == X_copy.nnz
assert_array_equal(X.toarray(), X_copy.toarray())
def test_optics_predecessor_correction_ordering():
"""Check that cluster correction using predecessor is working as expected.
In the following example, the predecessor correction was not working properly
since it was not using the right indices.
This non-regression test check that reordering the data does not change the results.
Non-regression test for:
https://github.com/scikit-learn/scikit-learn/issues/26324
"""
X_1 = np.array([1, 2, 3, 1, 8, 8, 7, 100]).reshape(-1, 1)
reorder = [0, 1, 2, 4, 5, 6, 7, 3]
X_2 = X_1[reorder]
optics_1 = OPTICS(min_samples=3, metric="euclidean").fit(X_1)
optics_2 = OPTICS(min_samples=3, metric="euclidean").fit(X_2)
assert_array_equal(optics_1.labels_[reorder], optics_2.labels_)

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"""Testing for Spectral Clustering methods"""
import pickle
import re
import numpy as np
import pytest
from scipy.linalg import LinAlgError
from sklearn.cluster import SpectralClustering, spectral_clustering
from sklearn.cluster._spectral import cluster_qr, discretize
from sklearn.datasets import make_blobs
from sklearn.feature_extraction import img_to_graph
from sklearn.metrics import adjusted_rand_score
from sklearn.metrics.pairwise import kernel_metrics, rbf_kernel
from sklearn.neighbors import NearestNeighbors
from sklearn.utils import check_random_state
from sklearn.utils._testing import assert_array_equal
from sklearn.utils.fixes import COO_CONTAINERS, CSR_CONTAINERS
try:
from pyamg import smoothed_aggregation_solver # noqa: F401
amg_loaded = True
except ImportError:
amg_loaded = False
centers = np.array([[1, 1], [-1, -1], [1, -1]]) + 10
X, _ = make_blobs(
n_samples=60,
n_features=2,
centers=centers,
cluster_std=0.4,
shuffle=True,
random_state=0,
)
@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
@pytest.mark.parametrize("eigen_solver", ("arpack", "lobpcg"))
@pytest.mark.parametrize("assign_labels", ("kmeans", "discretize", "cluster_qr"))
def test_spectral_clustering(
eigen_solver, assign_labels, csr_container, global_random_seed
):
S = np.array(
[
[1.0, 1.0, 1.0, 0.2, 0.0, 0.0, 0.0],
[1.0, 1.0, 1.0, 0.2, 0.0, 0.0, 0.0],
[1.0, 1.0, 1.0, 0.2, 0.0, 0.0, 0.0],
[0.2, 0.2, 0.2, 1.0, 1.0, 1.0, 1.0],
[0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0],
[0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0],
[0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0],
]
)
for mat in (S, csr_container(S)):
model = SpectralClustering(
random_state=global_random_seed,
n_clusters=2,
affinity="precomputed",
eigen_solver=eigen_solver,
assign_labels=assign_labels,
).fit(mat)
labels = model.labels_
if labels[0] == 0:
labels = 1 - labels
assert adjusted_rand_score(labels, [1, 1, 1, 0, 0, 0, 0]) == 1
model_copy = pickle.loads(pickle.dumps(model))
assert model_copy.n_clusters == model.n_clusters
assert model_copy.eigen_solver == model.eigen_solver
assert_array_equal(model_copy.labels_, model.labels_)
@pytest.mark.parametrize("coo_container", COO_CONTAINERS)
@pytest.mark.parametrize("assign_labels", ("kmeans", "discretize", "cluster_qr"))
def test_spectral_clustering_sparse(assign_labels, coo_container, global_random_seed):
X, y = make_blobs(
n_samples=20,
random_state=global_random_seed,
centers=[[1, 1], [-1, -1]],
cluster_std=0.01,
)
S = rbf_kernel(X, gamma=1)
S = np.maximum(S - 1e-4, 0)
S = coo_container(S)
labels = (
SpectralClustering(
random_state=global_random_seed,
n_clusters=2,
affinity="precomputed",
assign_labels=assign_labels,
)
.fit(S)
.labels_
)
assert adjusted_rand_score(y, labels) == 1
def test_precomputed_nearest_neighbors_filtering(global_random_seed):
# Test precomputed graph filtering when containing too many neighbors
X, y = make_blobs(
n_samples=250,
random_state=global_random_seed,
centers=[[1, 1, 1], [-1, -1, -1]],
cluster_std=0.01,
)
n_neighbors = 2
results = []
for additional_neighbors in [0, 10]:
nn = NearestNeighbors(n_neighbors=n_neighbors + additional_neighbors).fit(X)
graph = nn.kneighbors_graph(X, mode="distance")
labels = (
SpectralClustering(
random_state=global_random_seed,
n_clusters=2,
affinity="precomputed_nearest_neighbors",
n_neighbors=n_neighbors,
)
.fit(graph)
.labels_
)
results.append(labels)
assert_array_equal(results[0], results[1])
def test_affinities(global_random_seed):
# Note: in the following, random_state has been selected to have
# a dataset that yields a stable eigen decomposition both when built
# on OSX and Linux
X, y = make_blobs(
n_samples=20, random_state=0, centers=[[1, 1], [-1, -1]], cluster_std=0.01
)
# nearest neighbors affinity
sp = SpectralClustering(n_clusters=2, affinity="nearest_neighbors", random_state=0)
with pytest.warns(UserWarning, match="not fully connected"):
sp.fit(X)
assert adjusted_rand_score(y, sp.labels_) == 1
sp = SpectralClustering(n_clusters=2, gamma=2, random_state=global_random_seed)
labels = sp.fit(X).labels_
assert adjusted_rand_score(y, labels) == 1
X = check_random_state(10).rand(10, 5) * 10
kernels_available = kernel_metrics()
for kern in kernels_available:
# Additive chi^2 gives a negative similarity matrix which
# doesn't make sense for spectral clustering
if kern != "additive_chi2":
sp = SpectralClustering(n_clusters=2, affinity=kern, random_state=0)
labels = sp.fit(X).labels_
assert (X.shape[0],) == labels.shape
sp = SpectralClustering(n_clusters=2, affinity=lambda x, y: 1, random_state=0)
labels = sp.fit(X).labels_
assert (X.shape[0],) == labels.shape
def histogram(x, y, **kwargs):
# Histogram kernel implemented as a callable.
assert kwargs == {} # no kernel_params that we didn't ask for
return np.minimum(x, y).sum()
sp = SpectralClustering(n_clusters=2, affinity=histogram, random_state=0)
labels = sp.fit(X).labels_
assert (X.shape[0],) == labels.shape
def test_cluster_qr(global_random_seed):
# cluster_qr by itself should not be used for clustering generic data
# other than the rows of the eigenvectors within spectral clustering,
# but cluster_qr must still preserve the labels for different dtypes
# of the generic fixed input even if the labels may be meaningless.
random_state = np.random.RandomState(seed=global_random_seed)
n_samples, n_components = 10, 5
data = random_state.randn(n_samples, n_components)
labels_float64 = cluster_qr(data.astype(np.float64))
# Each sample is assigned a cluster identifier
assert labels_float64.shape == (n_samples,)
# All components should be covered by the assignment
assert np.array_equal(np.unique(labels_float64), np.arange(n_components))
# Single precision data should yield the same cluster assignments
labels_float32 = cluster_qr(data.astype(np.float32))
assert np.array_equal(labels_float64, labels_float32)
def test_cluster_qr_permutation_invariance(global_random_seed):
# cluster_qr must be invariant to sample permutation.
random_state = np.random.RandomState(seed=global_random_seed)
n_samples, n_components = 100, 5
data = random_state.randn(n_samples, n_components)
perm = random_state.permutation(n_samples)
assert np.array_equal(
cluster_qr(data)[perm],
cluster_qr(data[perm]),
)
@pytest.mark.parametrize("coo_container", COO_CONTAINERS)
@pytest.mark.parametrize("n_samples", [50, 100, 150, 500])
def test_discretize(n_samples, coo_container, global_random_seed):
# Test the discretize using a noise assignment matrix
random_state = np.random.RandomState(seed=global_random_seed)
for n_class in range(2, 10):
# random class labels
y_true = random_state.randint(0, n_class + 1, n_samples)
y_true = np.array(y_true, float)
# noise class assignment matrix
y_indicator = coo_container(
(np.ones(n_samples), (np.arange(n_samples), y_true)),
shape=(n_samples, n_class + 1),
)
y_true_noisy = y_indicator.toarray() + 0.1 * random_state.randn(
n_samples, n_class + 1
)
y_pred = discretize(y_true_noisy, random_state=random_state)
assert adjusted_rand_score(y_true, y_pred) > 0.8
def test_spectral_clustering_with_arpack_amg_solvers(global_random_seed):
# Test that spectral_clustering is the same for arpack and amg solver
# Based on toy example from plot_segmentation_toy.py
# a small two coin image
x, y = np.indices((40, 40))
center1, center2 = (14, 12), (20, 25)
radius1, radius2 = 8, 7
circle1 = (x - center1[0]) ** 2 + (y - center1[1]) ** 2 < radius1**2
circle2 = (x - center2[0]) ** 2 + (y - center2[1]) ** 2 < radius2**2
circles = circle1 | circle2
mask = circles.copy()
img = circles.astype(float)
graph = img_to_graph(img, mask=mask)
graph.data = np.exp(-graph.data / graph.data.std())
labels_arpack = spectral_clustering(
graph, n_clusters=2, eigen_solver="arpack", random_state=global_random_seed
)
assert len(np.unique(labels_arpack)) == 2
if amg_loaded:
labels_amg = spectral_clustering(
graph, n_clusters=2, eigen_solver="amg", random_state=global_random_seed
)
assert adjusted_rand_score(labels_arpack, labels_amg) == 1
else:
with pytest.raises(ValueError):
spectral_clustering(graph, n_clusters=2, eigen_solver="amg", random_state=0)
def test_n_components(global_random_seed):
# Test that after adding n_components, result is different and
# n_components = n_clusters by default
X, y = make_blobs(
n_samples=20,
random_state=global_random_seed,
centers=[[1, 1], [-1, -1]],
cluster_std=0.01,
)
sp = SpectralClustering(n_clusters=2, random_state=global_random_seed)
labels = sp.fit(X).labels_
# set n_components = n_cluster and test if result is the same
labels_same_ncomp = (
SpectralClustering(
n_clusters=2, n_components=2, random_state=global_random_seed
)
.fit(X)
.labels_
)
# test that n_components=n_clusters by default
assert_array_equal(labels, labels_same_ncomp)
# test that n_components affect result
# n_clusters=8 by default, and set n_components=2
labels_diff_ncomp = (
SpectralClustering(n_components=2, random_state=global_random_seed)
.fit(X)
.labels_
)
assert not np.array_equal(labels, labels_diff_ncomp)
@pytest.mark.parametrize("assign_labels", ("kmeans", "discretize", "cluster_qr"))
def test_verbose(assign_labels, capsys):
# Check verbose mode of KMeans for better coverage.
X, y = make_blobs(
n_samples=20, random_state=0, centers=[[1, 1], [-1, -1]], cluster_std=0.01
)
SpectralClustering(n_clusters=2, random_state=42, verbose=1).fit(X)
captured = capsys.readouterr()
assert re.search(r"Computing label assignment using", captured.out)
if assign_labels == "kmeans":
assert re.search(r"Initialization complete", captured.out)
assert re.search(r"Iteration [0-9]+, inertia", captured.out)
def test_spectral_clustering_np_matrix_raises():
"""Check that spectral_clustering raises an informative error when passed
an np.matrix. See #10993"""
X = np.matrix([[0.0, 2.0], [2.0, 0.0]])
msg = r"np\.matrix is not supported. Please convert to a numpy array"
with pytest.raises(TypeError, match=msg):
spectral_clustering(X)
def test_spectral_clustering_not_infinite_loop(capsys, monkeypatch):
"""Check that discretize raises LinAlgError when svd never converges.
Non-regression test for #21380
"""
def new_svd(*args, **kwargs):
raise LinAlgError()
monkeypatch.setattr(np.linalg, "svd", new_svd)
vectors = np.ones((10, 4))
with pytest.raises(LinAlgError, match="SVD did not converge"):
discretize(vectors)