Intelegentny_Pszczelarz/.venv/Lib/site-packages/sklearn/ensemble/tests/test_voting.py
2023-06-19 00:49:18 +02:00

675 lines
23 KiB
Python

"""Testing for the VotingClassifier and VotingRegressor"""
import pytest
import re
import numpy as np
from sklearn.utils._testing import assert_almost_equal, assert_array_equal
from sklearn.utils._testing import assert_array_almost_equal
from sklearn.exceptions import NotFittedError
from sklearn.linear_model import LinearRegression
from sklearn.linear_model import LogisticRegression
from sklearn.naive_bayes import GaussianNB
from sklearn.ensemble import RandomForestClassifier
from sklearn.ensemble import RandomForestRegressor
from sklearn.ensemble import VotingClassifier, VotingRegressor
from sklearn.tree import DecisionTreeClassifier
from sklearn.tree import DecisionTreeRegressor
from sklearn.model_selection import GridSearchCV
from sklearn import datasets
from sklearn.model_selection import cross_val_score, train_test_split
from sklearn.datasets import make_multilabel_classification
from sklearn.svm import SVC
from sklearn.multiclass import OneVsRestClassifier
from sklearn.neighbors import KNeighborsClassifier
from sklearn.base import BaseEstimator, ClassifierMixin, clone
from sklearn.dummy import DummyRegressor
from sklearn.preprocessing import StandardScaler
# Load datasets
iris = datasets.load_iris()
X, y = iris.data[:, 1:3], iris.target
# Scaled to solve ConvergenceWarning throw by Logistic Regression
X_scaled = StandardScaler().fit_transform(X)
X_r, y_r = datasets.load_diabetes(return_X_y=True)
@pytest.mark.parametrize(
"params, err_msg",
[
(
{"estimators": []},
"Invalid 'estimators' attribute, 'estimators' should be a non-empty list",
),
(
{"estimators": [("lr", LogisticRegression())], "weights": [1, 2]},
"Number of `estimators` and weights must be equal",
),
],
)
def test_voting_classifier_estimator_init(params, err_msg):
ensemble = VotingClassifier(**params)
with pytest.raises(ValueError, match=err_msg):
ensemble.fit(X, y)
def test_predictproba_hardvoting():
eclf = VotingClassifier(
estimators=[("lr1", LogisticRegression()), ("lr2", LogisticRegression())],
voting="hard",
)
msg = "predict_proba is not available when voting='hard'"
with pytest.raises(AttributeError, match=msg):
eclf.predict_proba
assert not hasattr(eclf, "predict_proba")
eclf.fit(X_scaled, y)
assert not hasattr(eclf, "predict_proba")
def test_notfitted():
eclf = VotingClassifier(
estimators=[("lr1", LogisticRegression()), ("lr2", LogisticRegression())],
voting="soft",
)
ereg = VotingRegressor([("dr", DummyRegressor())])
msg = (
"This %s instance is not fitted yet. Call 'fit'"
" with appropriate arguments before using this estimator."
)
with pytest.raises(NotFittedError, match=msg % "VotingClassifier"):
eclf.predict(X)
with pytest.raises(NotFittedError, match=msg % "VotingClassifier"):
eclf.predict_proba(X)
with pytest.raises(NotFittedError, match=msg % "VotingClassifier"):
eclf.transform(X)
with pytest.raises(NotFittedError, match=msg % "VotingRegressor"):
ereg.predict(X_r)
with pytest.raises(NotFittedError, match=msg % "VotingRegressor"):
ereg.transform(X_r)
def test_majority_label_iris(global_random_seed):
"""Check classification by majority label on dataset iris."""
clf1 = LogisticRegression(solver="liblinear", random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
clf3 = GaussianNB()
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)], voting="hard"
)
scores = cross_val_score(eclf, X, y, scoring="accuracy")
assert scores.mean() >= 0.9
def test_tie_situation():
"""Check voting classifier selects smaller class label in tie situation."""
clf1 = LogisticRegression(random_state=123, solver="liblinear")
clf2 = RandomForestClassifier(random_state=123)
eclf = VotingClassifier(estimators=[("lr", clf1), ("rf", clf2)], voting="hard")
assert clf1.fit(X, y).predict(X)[73] == 2
assert clf2.fit(X, y).predict(X)[73] == 1
assert eclf.fit(X, y).predict(X)[73] == 1
def test_weights_iris(global_random_seed):
"""Check classification by average probabilities on dataset iris."""
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
clf3 = GaussianNB()
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)],
voting="soft",
weights=[1, 2, 10],
)
scores = cross_val_score(eclf, X_scaled, y, scoring="accuracy")
assert scores.mean() >= 0.9
def test_weights_regressor():
"""Check weighted average regression prediction on diabetes dataset."""
reg1 = DummyRegressor(strategy="mean")
reg2 = DummyRegressor(strategy="median")
reg3 = DummyRegressor(strategy="quantile", quantile=0.2)
ereg = VotingRegressor(
[("mean", reg1), ("median", reg2), ("quantile", reg3)], weights=[1, 2, 10]
)
X_r_train, X_r_test, y_r_train, y_r_test = train_test_split(
X_r, y_r, test_size=0.25
)
reg1_pred = reg1.fit(X_r_train, y_r_train).predict(X_r_test)
reg2_pred = reg2.fit(X_r_train, y_r_train).predict(X_r_test)
reg3_pred = reg3.fit(X_r_train, y_r_train).predict(X_r_test)
ereg_pred = ereg.fit(X_r_train, y_r_train).predict(X_r_test)
avg = np.average(
np.asarray([reg1_pred, reg2_pred, reg3_pred]), axis=0, weights=[1, 2, 10]
)
assert_almost_equal(ereg_pred, avg, decimal=2)
ereg_weights_none = VotingRegressor(
[("mean", reg1), ("median", reg2), ("quantile", reg3)], weights=None
)
ereg_weights_equal = VotingRegressor(
[("mean", reg1), ("median", reg2), ("quantile", reg3)], weights=[1, 1, 1]
)
ereg_weights_none.fit(X_r_train, y_r_train)
ereg_weights_equal.fit(X_r_train, y_r_train)
ereg_none_pred = ereg_weights_none.predict(X_r_test)
ereg_equal_pred = ereg_weights_equal.predict(X_r_test)
assert_almost_equal(ereg_none_pred, ereg_equal_pred, decimal=2)
def test_predict_on_toy_problem(global_random_seed):
"""Manually check predicted class labels for toy dataset."""
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
clf3 = GaussianNB()
X = np.array(
[[-1.1, -1.5], [-1.2, -1.4], [-3.4, -2.2], [1.1, 1.2], [2.1, 1.4], [3.1, 2.3]]
)
y = np.array([1, 1, 1, 2, 2, 2])
assert_array_equal(clf1.fit(X, y).predict(X), [1, 1, 1, 2, 2, 2])
assert_array_equal(clf2.fit(X, y).predict(X), [1, 1, 1, 2, 2, 2])
assert_array_equal(clf3.fit(X, y).predict(X), [1, 1, 1, 2, 2, 2])
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)],
voting="hard",
weights=[1, 1, 1],
)
assert_array_equal(eclf.fit(X, y).predict(X), [1, 1, 1, 2, 2, 2])
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)],
voting="soft",
weights=[1, 1, 1],
)
assert_array_equal(eclf.fit(X, y).predict(X), [1, 1, 1, 2, 2, 2])
def test_predict_proba_on_toy_problem():
"""Calculate predicted probabilities on toy dataset."""
clf1 = LogisticRegression(random_state=123)
clf2 = RandomForestClassifier(random_state=123)
clf3 = GaussianNB()
X = np.array([[-1.1, -1.5], [-1.2, -1.4], [-3.4, -2.2], [1.1, 1.2]])
y = np.array([1, 1, 2, 2])
clf1_res = np.array(
[
[0.59790391, 0.40209609],
[0.57622162, 0.42377838],
[0.50728456, 0.49271544],
[0.40241774, 0.59758226],
]
)
clf2_res = np.array([[0.8, 0.2], [0.8, 0.2], [0.2, 0.8], [0.3, 0.7]])
clf3_res = np.array(
[[0.9985082, 0.0014918], [0.99845843, 0.00154157], [0.0, 1.0], [0.0, 1.0]]
)
t00 = (2 * clf1_res[0][0] + clf2_res[0][0] + clf3_res[0][0]) / 4
t11 = (2 * clf1_res[1][1] + clf2_res[1][1] + clf3_res[1][1]) / 4
t21 = (2 * clf1_res[2][1] + clf2_res[2][1] + clf3_res[2][1]) / 4
t31 = (2 * clf1_res[3][1] + clf2_res[3][1] + clf3_res[3][1]) / 4
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)],
voting="soft",
weights=[2, 1, 1],
)
eclf_res = eclf.fit(X, y).predict_proba(X)
assert_almost_equal(t00, eclf_res[0][0], decimal=1)
assert_almost_equal(t11, eclf_res[1][1], decimal=1)
assert_almost_equal(t21, eclf_res[2][1], decimal=1)
assert_almost_equal(t31, eclf_res[3][1], decimal=1)
with pytest.raises(
AttributeError, match="predict_proba is not available when voting='hard'"
):
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)], voting="hard"
)
eclf.fit(X, y).predict_proba(X)
def test_multilabel():
"""Check if error is raised for multilabel classification."""
X, y = make_multilabel_classification(
n_classes=2, n_labels=1, allow_unlabeled=False, random_state=123
)
clf = OneVsRestClassifier(SVC(kernel="linear"))
eclf = VotingClassifier(estimators=[("ovr", clf)], voting="hard")
try:
eclf.fit(X, y)
except NotImplementedError:
return
def test_gridsearch():
"""Check GridSearch support."""
clf1 = LogisticRegression(random_state=1)
clf2 = RandomForestClassifier(random_state=1, n_estimators=3)
clf3 = GaussianNB()
eclf = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)], voting="soft"
)
params = {
"lr__C": [1.0, 100.0],
"voting": ["soft", "hard"],
"weights": [[0.5, 0.5, 0.5], [1.0, 0.5, 0.5]],
}
grid = GridSearchCV(estimator=eclf, param_grid=params, cv=2)
grid.fit(X_scaled, y)
def test_parallel_fit(global_random_seed):
"""Check parallel backend of VotingClassifier on toy dataset."""
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
clf3 = GaussianNB()
X = np.array([[-1.1, -1.5], [-1.2, -1.4], [-3.4, -2.2], [1.1, 1.2]])
y = np.array([1, 1, 2, 2])
eclf1 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)], voting="soft", n_jobs=1
).fit(X, y)
eclf2 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)], voting="soft", n_jobs=2
).fit(X, y)
assert_array_equal(eclf1.predict(X), eclf2.predict(X))
assert_array_almost_equal(eclf1.predict_proba(X), eclf2.predict_proba(X))
def test_sample_weight(global_random_seed):
"""Tests sample_weight parameter of VotingClassifier"""
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
clf3 = SVC(probability=True, random_state=global_random_seed)
eclf1 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("svc", clf3)], voting="soft"
).fit(X_scaled, y, sample_weight=np.ones((len(y),)))
eclf2 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("svc", clf3)], voting="soft"
).fit(X_scaled, y)
assert_array_equal(eclf1.predict(X_scaled), eclf2.predict(X_scaled))
assert_array_almost_equal(
eclf1.predict_proba(X_scaled), eclf2.predict_proba(X_scaled)
)
sample_weight = np.random.RandomState(global_random_seed).uniform(size=(len(y),))
eclf3 = VotingClassifier(estimators=[("lr", clf1)], voting="soft")
eclf3.fit(X_scaled, y, sample_weight)
clf1.fit(X_scaled, y, sample_weight)
assert_array_equal(eclf3.predict(X_scaled), clf1.predict(X_scaled))
assert_array_almost_equal(
eclf3.predict_proba(X_scaled), clf1.predict_proba(X_scaled)
)
# check that an error is raised and indicative if sample_weight is not
# supported.
clf4 = KNeighborsClassifier()
eclf3 = VotingClassifier(
estimators=[("lr", clf1), ("svc", clf3), ("knn", clf4)], voting="soft"
)
msg = "Underlying estimator KNeighborsClassifier does not support sample weights."
with pytest.raises(TypeError, match=msg):
eclf3.fit(X_scaled, y, sample_weight)
# check that _fit_single_estimator will raise the right error
# it should raise the original error if this is not linked to sample_weight
class ClassifierErrorFit(ClassifierMixin, BaseEstimator):
def fit(self, X_scaled, y, sample_weight):
raise TypeError("Error unrelated to sample_weight.")
clf = ClassifierErrorFit()
with pytest.raises(TypeError, match="Error unrelated to sample_weight"):
clf.fit(X_scaled, y, sample_weight=sample_weight)
def test_sample_weight_kwargs():
"""Check that VotingClassifier passes sample_weight as kwargs"""
class MockClassifier(ClassifierMixin, BaseEstimator):
"""Mock Classifier to check that sample_weight is received as kwargs"""
def fit(self, X, y, *args, **sample_weight):
assert "sample_weight" in sample_weight
clf = MockClassifier()
eclf = VotingClassifier(estimators=[("mock", clf)], voting="soft")
# Should not raise an error.
eclf.fit(X, y, sample_weight=np.ones((len(y),)))
def test_voting_classifier_set_params(global_random_seed):
# check equivalence in the output when setting underlying estimators
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(
n_estimators=10, random_state=global_random_seed, max_depth=None
)
clf3 = GaussianNB()
eclf1 = VotingClassifier(
[("lr", clf1), ("rf", clf2)], voting="soft", weights=[1, 2]
).fit(X_scaled, y)
eclf2 = VotingClassifier(
[("lr", clf1), ("nb", clf3)], voting="soft", weights=[1, 2]
)
eclf2.set_params(nb=clf2).fit(X_scaled, y)
assert_array_equal(eclf1.predict(X_scaled), eclf2.predict(X_scaled))
assert_array_almost_equal(
eclf1.predict_proba(X_scaled), eclf2.predict_proba(X_scaled)
)
assert eclf2.estimators[0][1].get_params() == clf1.get_params()
assert eclf2.estimators[1][1].get_params() == clf2.get_params()
def test_set_estimator_drop():
# VotingClassifier set_params should be able to set estimators as drop
# Test predict
clf1 = LogisticRegression(random_state=123)
clf2 = RandomForestClassifier(n_estimators=10, random_state=123)
clf3 = GaussianNB()
eclf1 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("nb", clf3)],
voting="hard",
weights=[1, 0, 0.5],
).fit(X, y)
eclf2 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("nb", clf3)],
voting="hard",
weights=[1, 1, 0.5],
)
eclf2.set_params(rf="drop").fit(X, y)
assert_array_equal(eclf1.predict(X), eclf2.predict(X))
assert dict(eclf2.estimators)["rf"] == "drop"
assert len(eclf2.estimators_) == 2
assert all(
isinstance(est, (LogisticRegression, GaussianNB)) for est in eclf2.estimators_
)
assert eclf2.get_params()["rf"] == "drop"
eclf1.set_params(voting="soft").fit(X, y)
eclf2.set_params(voting="soft").fit(X, y)
assert_array_equal(eclf1.predict(X), eclf2.predict(X))
assert_array_almost_equal(eclf1.predict_proba(X), eclf2.predict_proba(X))
msg = "All estimators are dropped. At least one is required"
with pytest.raises(ValueError, match=msg):
eclf2.set_params(lr="drop", rf="drop", nb="drop").fit(X, y)
# Test soft voting transform
X1 = np.array([[1], [2]])
y1 = np.array([1, 2])
eclf1 = VotingClassifier(
estimators=[("rf", clf2), ("nb", clf3)],
voting="soft",
weights=[0, 0.5],
flatten_transform=False,
).fit(X1, y1)
eclf2 = VotingClassifier(
estimators=[("rf", clf2), ("nb", clf3)],
voting="soft",
weights=[1, 0.5],
flatten_transform=False,
)
eclf2.set_params(rf="drop").fit(X1, y1)
assert_array_almost_equal(
eclf1.transform(X1),
np.array([[[0.7, 0.3], [0.3, 0.7]], [[1.0, 0.0], [0.0, 1.0]]]),
)
assert_array_almost_equal(eclf2.transform(X1), np.array([[[1.0, 0.0], [0.0, 1.0]]]))
eclf1.set_params(voting="hard")
eclf2.set_params(voting="hard")
assert_array_equal(eclf1.transform(X1), np.array([[0, 0], [1, 1]]))
assert_array_equal(eclf2.transform(X1), np.array([[0], [1]]))
def test_estimator_weights_format(global_random_seed):
# Test estimator weights inputs as list and array
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
eclf1 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2)], weights=[1, 2], voting="soft"
)
eclf2 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2)], weights=np.array((1, 2)), voting="soft"
)
eclf1.fit(X_scaled, y)
eclf2.fit(X_scaled, y)
assert_array_almost_equal(
eclf1.predict_proba(X_scaled), eclf2.predict_proba(X_scaled)
)
def test_transform(global_random_seed):
"""Check transform method of VotingClassifier on toy dataset."""
clf1 = LogisticRegression(random_state=global_random_seed)
clf2 = RandomForestClassifier(n_estimators=10, random_state=global_random_seed)
clf3 = GaussianNB()
X = np.array([[-1.1, -1.5], [-1.2, -1.4], [-3.4, -2.2], [1.1, 1.2]])
y = np.array([1, 1, 2, 2])
eclf1 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)], voting="soft"
).fit(X, y)
eclf2 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)],
voting="soft",
flatten_transform=True,
).fit(X, y)
eclf3 = VotingClassifier(
estimators=[("lr", clf1), ("rf", clf2), ("gnb", clf3)],
voting="soft",
flatten_transform=False,
).fit(X, y)
assert_array_equal(eclf1.transform(X).shape, (4, 6))
assert_array_equal(eclf2.transform(X).shape, (4, 6))
assert_array_equal(eclf3.transform(X).shape, (3, 4, 2))
assert_array_almost_equal(eclf1.transform(X), eclf2.transform(X))
assert_array_almost_equal(
eclf3.transform(X).swapaxes(0, 1).reshape((4, 6)), eclf2.transform(X)
)
@pytest.mark.parametrize(
"X, y, voter",
[
(
X,
y,
VotingClassifier(
[
("lr", LogisticRegression()),
("rf", RandomForestClassifier(n_estimators=5)),
]
),
),
(
X_r,
y_r,
VotingRegressor(
[
("lr", LinearRegression()),
("rf", RandomForestRegressor(n_estimators=5)),
]
),
),
],
)
def test_none_estimator_with_weights(X, y, voter):
# check that an estimator can be set to 'drop' and passing some weight
# regression test for
# https://github.com/scikit-learn/scikit-learn/issues/13777
voter = clone(voter)
# Scaled to solve ConvergenceWarning throw by Logistic Regression
X_scaled = StandardScaler().fit_transform(X)
voter.fit(X_scaled, y, sample_weight=np.ones(y.shape))
voter.set_params(lr="drop")
voter.fit(X_scaled, y, sample_weight=np.ones(y.shape))
y_pred = voter.predict(X_scaled)
assert y_pred.shape == y.shape
@pytest.mark.parametrize(
"est",
[
VotingRegressor(
estimators=[
("lr", LinearRegression()),
("tree", DecisionTreeRegressor(random_state=0)),
]
),
VotingClassifier(
estimators=[
("lr", LogisticRegression(random_state=0)),
("tree", DecisionTreeClassifier(random_state=0)),
]
),
],
ids=["VotingRegressor", "VotingClassifier"],
)
def test_n_features_in(est):
X = [[1, 2], [3, 4], [5, 6]]
y = [0, 1, 2]
assert not hasattr(est, "n_features_in_")
est.fit(X, y)
assert est.n_features_in_ == 2
@pytest.mark.parametrize(
"estimator",
[
VotingRegressor(
estimators=[
("lr", LinearRegression()),
("rf", RandomForestRegressor(random_state=123)),
],
verbose=True,
),
VotingClassifier(
estimators=[
("lr", LogisticRegression(random_state=123)),
("rf", RandomForestClassifier(random_state=123)),
],
verbose=True,
),
],
)
def test_voting_verbose(estimator, capsys):
X = np.array([[-1.1, -1.5], [-1.2, -1.4], [-3.4, -2.2], [1.1, 1.2]])
y = np.array([1, 1, 2, 2])
pattern = (
r"\[Voting\].*\(1 of 2\) Processing lr, total=.*\n"
r"\[Voting\].*\(2 of 2\) Processing rf, total=.*\n$"
)
estimator.fit(X, y)
assert re.match(pattern, capsys.readouterr()[0])
def test_get_features_names_out_regressor():
"""Check get_feature_names_out output for regressor."""
X = [[1, 2], [3, 4], [5, 6]]
y = [0, 1, 2]
voting = VotingRegressor(
estimators=[
("lr", LinearRegression()),
("tree", DecisionTreeRegressor(random_state=0)),
("ignore", "drop"),
]
)
voting.fit(X, y)
names_out = voting.get_feature_names_out()
expected_names = ["votingregressor_lr", "votingregressor_tree"]
assert_array_equal(names_out, expected_names)
@pytest.mark.parametrize(
"kwargs, expected_names",
[
(
{"voting": "soft", "flatten_transform": True},
[
"votingclassifier_lr0",
"votingclassifier_lr1",
"votingclassifier_lr2",
"votingclassifier_tree0",
"votingclassifier_tree1",
"votingclassifier_tree2",
],
),
({"voting": "hard"}, ["votingclassifier_lr", "votingclassifier_tree"]),
],
)
def test_get_features_names_out_classifier(kwargs, expected_names):
"""Check get_feature_names_out for classifier for different settings."""
X = [[1, 2], [3, 4], [5, 6], [1, 1.2]]
y = [0, 1, 2, 0]
voting = VotingClassifier(
estimators=[
("lr", LogisticRegression(random_state=0)),
("tree", DecisionTreeClassifier(random_state=0)),
],
**kwargs,
)
voting.fit(X, y)
X_trans = voting.transform(X)
names_out = voting.get_feature_names_out()
assert X_trans.shape[1] == len(expected_names)
assert_array_equal(names_out, expected_names)
def test_get_features_names_out_classifier_error():
"""Check that error is raised when voting="soft" and flatten_transform=False."""
X = [[1, 2], [3, 4], [5, 6]]
y = [0, 1, 2]
voting = VotingClassifier(
estimators=[
("lr", LogisticRegression(random_state=0)),
("tree", DecisionTreeClassifier(random_state=0)),
],
voting="soft",
flatten_transform=False,
)
voting.fit(X, y)
msg = (
"get_feature_names_out is not supported when `voting='soft'` and "
"`flatten_transform=False`"
)
with pytest.raises(ValueError, match=msg):
voting.get_feature_names_out()