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"""Meta-estimators for building composite models with transformers.
In addition to its current contents, this module will eventually be home to
refurbished versions of :class:`~sklearn.pipeline.Pipeline` and
:class:`~sklearn.pipeline.FeatureUnion`.
"""
# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
from sklearn.compose._column_transformer import (
ColumnTransformer,
make_column_selector,
make_column_transformer,
)
from sklearn.compose._target import TransformedTargetRegressor
__all__ = [
"ColumnTransformer",
"TransformedTargetRegressor",
"make_column_selector",
"make_column_transformer",
]

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# Authors: The scikit-learn developers
# SPDX-License-Identifier: BSD-3-Clause
import warnings
import numpy as np
from sklearn.base import BaseEstimator, RegressorMixin, _fit_context, clone
from sklearn.exceptions import NotFittedError
from sklearn.linear_model import LinearRegression
from sklearn.preprocessing import FunctionTransformer
from sklearn.utils import Bunch, _safe_indexing, check_array
from sklearn.utils._metadata_requests import (
MetadataRouter,
MethodMapping,
_routing_enabled,
process_routing,
)
from sklearn.utils._param_validation import HasMethods
from sklearn.utils._tags import get_tags
from sklearn.utils.validation import check_is_fitted
__all__ = ["TransformedTargetRegressor"]
class TransformedTargetRegressor(RegressorMixin, BaseEstimator):
"""Meta-estimator to regress on a transformed target.
Useful for applying a non-linear transformation to the target `y` in
regression problems. This transformation can be given as a Transformer
such as the :class:`~sklearn.preprocessing.QuantileTransformer` or as a
function and its inverse such as `np.log` and `np.exp`.
The computation during :meth:`fit` is::
regressor.fit(X, func(y))
or::
regressor.fit(X, transformer.transform(y))
The computation during :meth:`predict` is::
inverse_func(regressor.predict(X))
or::
transformer.inverse_transform(regressor.predict(X))
Read more in the :ref:`User Guide <transformed_target_regressor>`.
.. versionadded:: 0.20
Parameters
----------
regressor : object, default=None
Regressor object such as derived from
:class:`~sklearn.base.RegressorMixin`. This regressor will
automatically be cloned each time prior to fitting. If `regressor is
None`, :class:`~sklearn.linear_model.LinearRegression` is created and used.
transformer : object, default=None
Estimator object such as derived from
:class:`~sklearn.base.TransformerMixin`. Cannot be set at the same time
as `func` and `inverse_func`. If `transformer is None` as well as
`func` and `inverse_func`, the transformer will be an identity
transformer. Note that the transformer will be cloned during fitting.
Also, the transformer is restricting `y` to be a numpy array.
func : function, default=None
Function to apply to `y` before passing to :meth:`fit`. Cannot be set
at the same time as `transformer`. If `func is None`, the function used will be
the identity function. If `func` is set, `inverse_func` also needs to be
provided. The function needs to return a 2-dimensional array.
inverse_func : function, default=None
Function to apply to the prediction of the regressor. Cannot be set at
the same time as `transformer`. The inverse function is used to return
predictions to the same space of the original training labels. If
`inverse_func` is set, `func` also needs to be provided. The inverse
function needs to return a 2-dimensional array.
check_inverse : bool, default=True
Whether to check that `transform` followed by `inverse_transform`
or `func` followed by `inverse_func` leads to the original targets.
Attributes
----------
regressor_ : object
Fitted regressor.
transformer_ : object
Transformer used in :meth:`fit` and :meth:`predict`.
n_features_in_ : int
Number of features seen during :term:`fit`. Only defined if the
underlying regressor exposes such an attribute when 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.preprocessing.FunctionTransformer : Construct a transformer from an
arbitrary callable.
Notes
-----
Internally, the target `y` is always converted into a 2-dimensional array
to be used by scikit-learn transformers. At the time of prediction, the
output will be reshaped to a have the same number of dimensions as `y`.
Examples
--------
>>> import numpy as np
>>> from sklearn.linear_model import LinearRegression
>>> from sklearn.compose import TransformedTargetRegressor
>>> tt = TransformedTargetRegressor(regressor=LinearRegression(),
... func=np.log, inverse_func=np.exp)
>>> X = np.arange(4).reshape(-1, 1)
>>> y = np.exp(2 * X).ravel()
>>> tt.fit(X, y)
TransformedTargetRegressor(...)
>>> tt.score(X, y)
1.0
>>> tt.regressor_.coef_
array([2.])
For a more detailed example use case refer to
:ref:`sphx_glr_auto_examples_compose_plot_transformed_target.py`.
"""
_parameter_constraints: dict = {
"regressor": [HasMethods(["fit", "predict"]), None],
"transformer": [HasMethods("transform"), None],
"func": [callable, None],
"inverse_func": [callable, None],
"check_inverse": ["boolean"],
}
def __init__(
self,
regressor=None,
*,
transformer=None,
func=None,
inverse_func=None,
check_inverse=True,
):
self.regressor = regressor
self.transformer = transformer
self.func = func
self.inverse_func = inverse_func
self.check_inverse = check_inverse
def _fit_transformer(self, y):
"""Check transformer and fit transformer.
Create the default transformer, fit it and make additional inverse
check on a subset (optional).
"""
if self.transformer is not None and (
self.func is not None or self.inverse_func is not None
):
raise ValueError(
"'transformer' and functions 'func'/'inverse_func' cannot both be set."
)
elif self.transformer is not None:
self.transformer_ = clone(self.transformer)
else:
if (self.func is not None and self.inverse_func is None) or (
self.func is None and self.inverse_func is not None
):
lacking_param, existing_param = (
("func", "inverse_func")
if self.func is None
else ("inverse_func", "func")
)
raise ValueError(
f"When '{existing_param}' is provided, '{lacking_param}' must also"
f" be provided. If {lacking_param} is supposed to be the default,"
" you need to explicitly pass it the identity function."
)
self.transformer_ = FunctionTransformer(
func=self.func,
inverse_func=self.inverse_func,
validate=True,
check_inverse=self.check_inverse,
)
# We are transforming the target here and not the features, so we set the
# output of FunctionTransformer() to be a numpy array (default) and to not
# depend on the global configuration:
self.transformer_.set_output(transform="default")
# XXX: sample_weight is not currently passed to the
# transformer. However, if transformer starts using sample_weight, the
# code should be modified accordingly. At the time to consider the
# sample_prop feature, it is also a good use case to be considered.
self.transformer_.fit(y)
if self.check_inverse:
idx_selected = slice(None, None, max(1, y.shape[0] // 10))
y_sel = _safe_indexing(y, idx_selected)
y_sel_t = self.transformer_.transform(y_sel)
if not np.allclose(y_sel, self.transformer_.inverse_transform(y_sel_t)):
warnings.warn(
(
"The provided functions or transformer are"
" not strictly inverse of each other. If"
" you are sure you want to proceed regardless"
", set 'check_inverse=False'"
),
UserWarning,
)
@_fit_context(
# TransformedTargetRegressor.regressor/transformer are not validated yet.
prefer_skip_nested_validation=False
)
def fit(self, X, y, **fit_params):
"""Fit the model according to the given training data.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
Training vector, where `n_samples` is the number of samples and
`n_features` is the number of features.
y : array-like of shape (n_samples,)
Target values.
**fit_params : dict
- If `enable_metadata_routing=False` (default): Parameters directly passed
to the `fit` method of the underlying regressor.
- If `enable_metadata_routing=True`: Parameters safely routed to the `fit`
method of the underlying regressor.
.. versionchanged:: 1.6
See :ref:`Metadata Routing User Guide <metadata_routing>` for
more details.
Returns
-------
self : object
Fitted estimator.
"""
if y is None:
raise ValueError(
f"This {self.__class__.__name__} estimator "
"requires y to be passed, but the target y is None."
)
y = check_array(
y,
input_name="y",
accept_sparse=False,
ensure_all_finite=True,
ensure_2d=False,
dtype="numeric",
allow_nd=True,
)
# store the number of dimension of the target to predict an array of
# similar shape at predict
self._training_dim = y.ndim
# transformers are designed to modify X which is 2d dimensional, we
# need to modify y accordingly.
if y.ndim == 1:
y_2d = y.reshape(-1, 1)
else:
y_2d = y
self._fit_transformer(y_2d)
# transform y and convert back to 1d array if needed
y_trans = self.transformer_.transform(y_2d)
# FIXME: a FunctionTransformer can return a 1D array even when validate
# is set to True. Therefore, we need to check the number of dimension
# first.
if y_trans.ndim == 2 and y_trans.shape[1] == 1 and self._training_dim == 1:
y_trans = y_trans.squeeze(axis=1)
self.regressor_ = self._get_regressor(get_clone=True)
if _routing_enabled():
routed_params = process_routing(self, "fit", **fit_params)
else:
routed_params = Bunch(regressor=Bunch(fit=fit_params))
self.regressor_.fit(X, y_trans, **routed_params.regressor.fit)
if hasattr(self.regressor_, "feature_names_in_"):
self.feature_names_in_ = self.regressor_.feature_names_in_
return self
def predict(self, X, **predict_params):
"""Predict using the base regressor, applying inverse.
The regressor is used to predict and the `inverse_func` or
`inverse_transform` is applied before returning the prediction.
Parameters
----------
X : {array-like, sparse matrix} of shape (n_samples, n_features)
Samples.
**predict_params : dict of str -> object
- If `enable_metadata_routing=False` (default): Parameters directly passed
to the `predict` method of the underlying regressor.
- If `enable_metadata_routing=True`: Parameters safely routed to the
`predict` method of the underlying regressor.
.. versionchanged:: 1.6
See :ref:`Metadata Routing User Guide <metadata_routing>`
for more details.
Returns
-------
y_hat : ndarray of shape (n_samples,)
Predicted values.
"""
check_is_fitted(self)
if _routing_enabled():
routed_params = process_routing(self, "predict", **predict_params)
else:
routed_params = Bunch(regressor=Bunch(predict=predict_params))
pred = self.regressor_.predict(X, **routed_params.regressor.predict)
if pred.ndim == 1:
pred_trans = self.transformer_.inverse_transform(pred.reshape(-1, 1))
else:
pred_trans = self.transformer_.inverse_transform(pred)
if (
self._training_dim == 1
and pred_trans.ndim == 2
and pred_trans.shape[1] == 1
):
pred_trans = pred_trans.squeeze(axis=1)
return pred_trans
def __sklearn_tags__(self):
regressor = self._get_regressor()
tags = super().__sklearn_tags__()
tags.regressor_tags.poor_score = True
tags.input_tags.sparse = get_tags(regressor).input_tags.sparse
tags.target_tags.multi_output = get_tags(regressor).target_tags.multi_output
return tags
@property
def n_features_in_(self):
"""Number of features seen during :term:`fit`."""
# For consistency with other estimators we raise an AttributeError so
# that hasattr() returns False the estimator isn't fitted.
try:
check_is_fitted(self)
except NotFittedError as nfe:
raise AttributeError(
"{} object has no n_features_in_ attribute.".format(
self.__class__.__name__
)
) from nfe
return self.regressor_.n_features_in_
def get_metadata_routing(self):
"""Get metadata routing of this object.
Please check :ref:`User Guide <metadata_routing>` on how the routing
mechanism works.
.. versionadded:: 1.6
Returns
-------
routing : MetadataRouter
A :class:`~sklearn.utils.metadata_routing.MetadataRouter` encapsulating
routing information.
"""
router = MetadataRouter(owner=self).add(
regressor=self._get_regressor(),
method_mapping=MethodMapping()
.add(caller="fit", callee="fit")
.add(caller="predict", callee="predict"),
)
return router
def _get_regressor(self, get_clone=False):
if self.regressor is None:
return LinearRegression()
return clone(self.regressor) if get_clone else self.regressor

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import warnings
import numpy as np
import pytest
from sklearn import config_context, datasets
from sklearn.base import BaseEstimator, TransformerMixin, clone
from sklearn.compose import TransformedTargetRegressor
from sklearn.dummy import DummyRegressor
from sklearn.linear_model import LinearRegression, OrthogonalMatchingPursuit
from sklearn.pipeline import Pipeline
from sklearn.preprocessing import FunctionTransformer, StandardScaler
from sklearn.utils._testing import assert_allclose
friedman = datasets.make_friedman1(random_state=0)
def test_transform_target_regressor_error():
X, y = friedman
# provide a transformer and functions at the same time
regr = TransformedTargetRegressor(
regressor=LinearRegression(),
transformer=StandardScaler(),
func=np.exp,
inverse_func=np.log,
)
with pytest.raises(
ValueError,
match="'transformer' and functions 'func'/'inverse_func' cannot both be set.",
):
regr.fit(X, y)
# fit with sample_weight with a regressor which does not support it
sample_weight = np.ones((y.shape[0],))
regr = TransformedTargetRegressor(
regressor=OrthogonalMatchingPursuit(), transformer=StandardScaler()
)
with pytest.raises(
TypeError,
match=r"fit\(\) got an unexpected keyword argument 'sample_weight'",
):
regr.fit(X, y, sample_weight=sample_weight)
# one of (func, inverse_func) is given but the other one is not
regr = TransformedTargetRegressor(func=np.exp)
with pytest.raises(
ValueError,
match="When 'func' is provided, 'inverse_func' must also be provided",
):
regr.fit(X, y)
regr = TransformedTargetRegressor(inverse_func=np.log)
with pytest.raises(
ValueError,
match="When 'inverse_func' is provided, 'func' must also be provided",
):
regr.fit(X, y)
def test_transform_target_regressor_invertible():
X, y = friedman
regr = TransformedTargetRegressor(
regressor=LinearRegression(),
func=np.sqrt,
inverse_func=np.log,
check_inverse=True,
)
with pytest.warns(
UserWarning,
match=(r"The provided functions.* are not strictly inverse of each other"),
):
regr.fit(X, y)
regr = TransformedTargetRegressor(
regressor=LinearRegression(), func=np.sqrt, inverse_func=np.log
)
regr.set_params(check_inverse=False)
with warnings.catch_warnings():
warnings.simplefilter("error", UserWarning)
regr.fit(X, y)
def _check_standard_scaled(y, y_pred):
y_mean = np.mean(y, axis=0)
y_std = np.std(y, axis=0)
assert_allclose((y - y_mean) / y_std, y_pred)
def _check_shifted_by_one(y, y_pred):
assert_allclose(y + 1, y_pred)
def test_transform_target_regressor_functions():
X, y = friedman
regr = TransformedTargetRegressor(
regressor=LinearRegression(), func=np.log, inverse_func=np.exp
)
y_pred = regr.fit(X, y).predict(X)
# check the transformer output
y_tran = regr.transformer_.transform(y.reshape(-1, 1)).squeeze()
assert_allclose(np.log(y), y_tran)
assert_allclose(
y, regr.transformer_.inverse_transform(y_tran.reshape(-1, 1)).squeeze()
)
assert y.shape == y_pred.shape
assert_allclose(y_pred, regr.inverse_func(regr.regressor_.predict(X)))
# check the regressor output
lr = LinearRegression().fit(X, regr.func(y))
assert_allclose(regr.regressor_.coef_.ravel(), lr.coef_.ravel())
def test_transform_target_regressor_functions_multioutput():
X = friedman[0]
y = np.vstack((friedman[1], friedman[1] ** 2 + 1)).T
regr = TransformedTargetRegressor(
regressor=LinearRegression(), func=np.log, inverse_func=np.exp
)
y_pred = regr.fit(X, y).predict(X)
# check the transformer output
y_tran = regr.transformer_.transform(y)
assert_allclose(np.log(y), y_tran)
assert_allclose(y, regr.transformer_.inverse_transform(y_tran))
assert y.shape == y_pred.shape
assert_allclose(y_pred, regr.inverse_func(regr.regressor_.predict(X)))
# check the regressor output
lr = LinearRegression().fit(X, regr.func(y))
assert_allclose(regr.regressor_.coef_.ravel(), lr.coef_.ravel())
@pytest.mark.parametrize(
"X,y", [friedman, (friedman[0], np.vstack((friedman[1], friedman[1] ** 2 + 1)).T)]
)
def test_transform_target_regressor_1d_transformer(X, y):
# All transformer in scikit-learn expect 2D data. FunctionTransformer with
# validate=False lift this constraint without checking that the input is a
# 2D vector. We check the consistency of the data shape using a 1D and 2D y
# array.
transformer = FunctionTransformer(
func=lambda x: x + 1, inverse_func=lambda x: x - 1
)
regr = TransformedTargetRegressor(
regressor=LinearRegression(), transformer=transformer
)
y_pred = regr.fit(X, y).predict(X)
assert y.shape == y_pred.shape
# consistency forward transform
y_tran = regr.transformer_.transform(y)
_check_shifted_by_one(y, y_tran)
assert y.shape == y_pred.shape
# consistency inverse transform
assert_allclose(y, regr.transformer_.inverse_transform(y_tran).squeeze())
# consistency of the regressor
lr = LinearRegression()
transformer2 = clone(transformer)
lr.fit(X, transformer2.fit_transform(y))
y_lr_pred = lr.predict(X)
assert_allclose(y_pred, transformer2.inverse_transform(y_lr_pred))
assert_allclose(regr.regressor_.coef_, lr.coef_)
@pytest.mark.parametrize(
"X,y", [friedman, (friedman[0], np.vstack((friedman[1], friedman[1] ** 2 + 1)).T)]
)
def test_transform_target_regressor_2d_transformer(X, y):
# Check consistency with transformer accepting only 2D array and a 1D/2D y
# array.
transformer = StandardScaler()
regr = TransformedTargetRegressor(
regressor=LinearRegression(), transformer=transformer
)
y_pred = regr.fit(X, y).predict(X)
assert y.shape == y_pred.shape
# consistency forward transform
if y.ndim == 1: # create a 2D array and squeeze results
y_tran = regr.transformer_.transform(y.reshape(-1, 1))
else:
y_tran = regr.transformer_.transform(y)
_check_standard_scaled(y, y_tran.squeeze())
assert y.shape == y_pred.shape
# consistency inverse transform
assert_allclose(y, regr.transformer_.inverse_transform(y_tran).squeeze())
# consistency of the regressor
lr = LinearRegression()
transformer2 = clone(transformer)
if y.ndim == 1: # create a 2D array and squeeze results
lr.fit(X, transformer2.fit_transform(y.reshape(-1, 1)).squeeze())
y_lr_pred = lr.predict(X).reshape(-1, 1)
y_pred2 = transformer2.inverse_transform(y_lr_pred).squeeze()
else:
lr.fit(X, transformer2.fit_transform(y))
y_lr_pred = lr.predict(X)
y_pred2 = transformer2.inverse_transform(y_lr_pred)
assert_allclose(y_pred, y_pred2)
assert_allclose(regr.regressor_.coef_, lr.coef_)
def test_transform_target_regressor_2d_transformer_multioutput():
# Check consistency with transformer accepting only 2D array and a 2D y
# array.
X = friedman[0]
y = np.vstack((friedman[1], friedman[1] ** 2 + 1)).T
transformer = StandardScaler()
regr = TransformedTargetRegressor(
regressor=LinearRegression(), transformer=transformer
)
y_pred = regr.fit(X, y).predict(X)
assert y.shape == y_pred.shape
# consistency forward transform
y_tran = regr.transformer_.transform(y)
_check_standard_scaled(y, y_tran)
assert y.shape == y_pred.shape
# consistency inverse transform
assert_allclose(y, regr.transformer_.inverse_transform(y_tran).squeeze())
# consistency of the regressor
lr = LinearRegression()
transformer2 = clone(transformer)
lr.fit(X, transformer2.fit_transform(y))
y_lr_pred = lr.predict(X)
assert_allclose(y_pred, transformer2.inverse_transform(y_lr_pred))
assert_allclose(regr.regressor_.coef_, lr.coef_)
def test_transform_target_regressor_3d_target():
# Non-regression test for:
# https://github.com/scikit-learn/scikit-learn/issues/18866
# Check with a 3D target with a transformer that reshapes the target
X = friedman[0]
y = np.tile(friedman[1].reshape(-1, 1, 1), [1, 3, 2])
def flatten_data(data):
return data.reshape(data.shape[0], -1)
def unflatten_data(data):
return data.reshape(data.shape[0], -1, 2)
transformer = FunctionTransformer(func=flatten_data, inverse_func=unflatten_data)
regr = TransformedTargetRegressor(
regressor=LinearRegression(), transformer=transformer
)
y_pred = regr.fit(X, y).predict(X)
assert y.shape == y_pred.shape
def test_transform_target_regressor_multi_to_single():
X = friedman[0]
y = np.transpose([friedman[1], (friedman[1] ** 2 + 1)])
def func(y):
out = np.sqrt(y[:, 0] ** 2 + y[:, 1] ** 2)
return out[:, np.newaxis]
def inverse_func(y):
return y
tt = TransformedTargetRegressor(
func=func, inverse_func=inverse_func, check_inverse=False
)
tt.fit(X, y)
y_pred_2d_func = tt.predict(X)
assert y_pred_2d_func.shape == (100, 1)
# force that the function only return a 1D array
def func(y):
return np.sqrt(y[:, 0] ** 2 + y[:, 1] ** 2)
tt = TransformedTargetRegressor(
func=func, inverse_func=inverse_func, check_inverse=False
)
tt.fit(X, y)
y_pred_1d_func = tt.predict(X)
assert y_pred_1d_func.shape == (100, 1)
assert_allclose(y_pred_1d_func, y_pred_2d_func)
class DummyCheckerArrayTransformer(TransformerMixin, BaseEstimator):
def fit(self, X, y=None):
assert isinstance(X, np.ndarray)
return self
def transform(self, X):
assert isinstance(X, np.ndarray)
return X
def inverse_transform(self, X):
assert isinstance(X, np.ndarray)
return X
class DummyCheckerListRegressor(DummyRegressor):
def fit(self, X, y, sample_weight=None):
assert isinstance(X, list)
return super().fit(X, y, sample_weight)
def predict(self, X):
assert isinstance(X, list)
return super().predict(X)
def test_transform_target_regressor_ensure_y_array():
# check that the target ``y`` passed to the transformer will always be a
# numpy array. Similarly, if ``X`` is passed as a list, we check that the
# predictor receive as it is.
X, y = friedman
tt = TransformedTargetRegressor(
transformer=DummyCheckerArrayTransformer(),
regressor=DummyCheckerListRegressor(),
check_inverse=False,
)
tt.fit(X.tolist(), y.tolist())
tt.predict(X.tolist())
with pytest.raises(AssertionError):
tt.fit(X, y.tolist())
with pytest.raises(AssertionError):
tt.predict(X)
class DummyTransformer(TransformerMixin, BaseEstimator):
"""Dummy transformer which count how many time fit was called."""
def __init__(self, fit_counter=0):
self.fit_counter = fit_counter
def fit(self, X, y=None):
self.fit_counter += 1
return self
def transform(self, X):
return X
def inverse_transform(self, X):
return X
@pytest.mark.parametrize("check_inverse", [False, True])
def test_transform_target_regressor_count_fit(check_inverse):
# regression test for gh-issue #11618
# check that we only call a single time fit for the transformer
X, y = friedman
ttr = TransformedTargetRegressor(
transformer=DummyTransformer(), check_inverse=check_inverse
)
ttr.fit(X, y)
assert ttr.transformer_.fit_counter == 1
class DummyRegressorWithExtraFitParams(DummyRegressor):
def fit(self, X, y, sample_weight=None, check_input=True):
# on the test below we force this to false, we make sure this is
# actually passed to the regressor
assert not check_input
return super().fit(X, y, sample_weight)
def test_transform_target_regressor_pass_fit_parameters():
X, y = friedman
regr = TransformedTargetRegressor(
regressor=DummyRegressorWithExtraFitParams(), transformer=DummyTransformer()
)
regr.fit(X, y, check_input=False)
assert regr.transformer_.fit_counter == 1
def test_transform_target_regressor_route_pipeline():
X, y = friedman
regr = TransformedTargetRegressor(
regressor=DummyRegressorWithExtraFitParams(), transformer=DummyTransformer()
)
estimators = [("normalize", StandardScaler()), ("est", regr)]
pip = Pipeline(estimators)
pip.fit(X, y, **{"est__check_input": False})
assert regr.transformer_.fit_counter == 1
class DummyRegressorWithExtraPredictParams(DummyRegressor):
def predict(self, X, check_input=True):
# In the test below we make sure that the check input parameter is
# passed as false
self.predict_called = True
assert not check_input
return super().predict(X)
def test_transform_target_regressor_pass_extra_predict_parameters():
# Checks that predict kwargs are passed to regressor.
X, y = friedman
regr = TransformedTargetRegressor(
regressor=DummyRegressorWithExtraPredictParams(), transformer=DummyTransformer()
)
regr.fit(X, y)
regr.predict(X, check_input=False)
assert regr.regressor_.predict_called
@pytest.mark.parametrize("output_format", ["pandas", "polars"])
def test_transform_target_regressor_not_warns_with_global_output_set(output_format):
"""Test that TransformedTargetRegressor will not raise warnings if
set_config(transform_output="pandas"/"polars") is set globally; regression test for
issue #29361."""
X, y = datasets.make_regression()
y = np.abs(y) + 1
with config_context(transform_output=output_format):
with warnings.catch_warnings():
warnings.simplefilter("error")
TransformedTargetRegressor(
regressor=LinearRegression(), func=np.log, inverse_func=np.exp
).fit(X, y)
class ValidateDimensionRegressor(BaseEstimator):
"""A regressor that expects the target to have a specific number of dimensions."""
def __init__(self, ndim):
self.ndim = ndim
def fit(self, X, y):
assert y.ndim == self.ndim
def predict(self, X):
pass # pragma: no cover
@pytest.mark.parametrize("ndim", [1, 2])
def test_transform_target_regressor_preserves_input_shape(ndim):
"""Check that TransformedTargetRegressor internally preserves the shape of the input
non-regression test for issue #26530.
"""
X, y = datasets.make_regression(n_samples=10, n_features=5, random_state=42)
if ndim == 2:
y = y.reshape(-1, 1)
regr = TransformedTargetRegressor(regressor=ValidateDimensionRegressor(ndim))
regr.fit(X, y)