"""
Testing for the forest module (sklearn.ensemble.forest).
"""

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

import itertools
import math
import pickle
from collections import defaultdict
from functools import partial
from itertools import combinations, product
from typing import Any, Dict
from unittest.mock import patch

import joblib
import numpy as np
import pytest
from scipy.special import comb

import sklearn
from sklearn import clone, datasets
from sklearn.datasets import make_classification, make_hastie_10_2
from sklearn.decomposition import TruncatedSVD
from sklearn.dummy import DummyRegressor
from sklearn.ensemble import (
    ExtraTreesClassifier,
    ExtraTreesRegressor,
    RandomForestClassifier,
    RandomForestRegressor,
    RandomTreesEmbedding,
)
from sklearn.ensemble._forest import (
    _generate_unsampled_indices,
    _get_n_samples_bootstrap,
)
from sklearn.exceptions import NotFittedError
from sklearn.metrics import (
    explained_variance_score,
    f1_score,
    mean_poisson_deviance,
    mean_squared_error,
)
from sklearn.model_selection import GridSearchCV, cross_val_score, train_test_split
from sklearn.svm import LinearSVC
from sklearn.tree._classes import SPARSE_SPLITTERS
from sklearn.utils._testing import (
    _convert_container,
    assert_allclose,
    assert_almost_equal,
    assert_array_almost_equal,
    assert_array_equal,
    ignore_warnings,
    skip_if_no_parallel,
)
from sklearn.utils.fixes import COO_CONTAINERS, CSC_CONTAINERS, CSR_CONTAINERS
from sklearn.utils.multiclass import type_of_target
from sklearn.utils.parallel import Parallel
from sklearn.utils.validation import check_random_state

# toy sample
X = [[-2, -1], [-1, -1], [-1, -2], [1, 1], [1, 2], [2, 1]]
y = [-1, -1, -1, 1, 1, 1]
T = [[-1, -1], [2, 2], [3, 2]]
true_result = [-1, 1, 1]

# Larger classification sample used for testing feature importances
X_large, y_large = datasets.make_classification(
    n_samples=500,
    n_features=10,
    n_informative=3,
    n_redundant=0,
    n_repeated=0,
    shuffle=False,
    random_state=0,
)

# also load the iris dataset
# and randomly permute it
iris = datasets.load_iris()
rng = check_random_state(0)
perm = rng.permutation(iris.target.size)
iris.data = iris.data[perm]
iris.target = iris.target[perm]

# Make regression dataset
X_reg, y_reg = datasets.make_regression(n_samples=500, n_features=10, random_state=1)

# also make a hastie_10_2 dataset
hastie_X, hastie_y = datasets.make_hastie_10_2(n_samples=20, random_state=1)
hastie_X = hastie_X.astype(np.float32)

# Get the default backend in joblib to test parallelism and interaction with
# different backends
DEFAULT_JOBLIB_BACKEND = joblib.parallel.get_active_backend()[0].__class__

FOREST_CLASSIFIERS = {
    "ExtraTreesClassifier": ExtraTreesClassifier,
    "RandomForestClassifier": RandomForestClassifier,
}

FOREST_REGRESSORS = {
    "ExtraTreesRegressor": ExtraTreesRegressor,
    "RandomForestRegressor": RandomForestRegressor,
}

FOREST_TRANSFORMERS = {
    "RandomTreesEmbedding": RandomTreesEmbedding,
}

FOREST_ESTIMATORS: Dict[str, Any] = dict()
FOREST_ESTIMATORS.update(FOREST_CLASSIFIERS)
FOREST_ESTIMATORS.update(FOREST_REGRESSORS)
FOREST_ESTIMATORS.update(FOREST_TRANSFORMERS)

FOREST_CLASSIFIERS_REGRESSORS: Dict[str, Any] = FOREST_CLASSIFIERS.copy()
FOREST_CLASSIFIERS_REGRESSORS.update(FOREST_REGRESSORS)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_classification_toy(name):
    """Check classification on a toy dataset."""
    ForestClassifier = FOREST_CLASSIFIERS[name]

    clf = ForestClassifier(n_estimators=10, random_state=1)
    clf.fit(X, y)
    assert_array_equal(clf.predict(T), true_result)
    assert 10 == len(clf)

    clf = ForestClassifier(n_estimators=10, max_features=1, random_state=1)
    clf.fit(X, y)
    assert_array_equal(clf.predict(T), true_result)
    assert 10 == len(clf)

    # also test apply
    leaf_indices = clf.apply(X)
    assert leaf_indices.shape == (len(X), clf.n_estimators)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
@pytest.mark.parametrize("criterion", ("gini", "log_loss"))
def test_iris_criterion(name, criterion):
    # Check consistency on dataset iris.
    ForestClassifier = FOREST_CLASSIFIERS[name]

    clf = ForestClassifier(n_estimators=10, criterion=criterion, random_state=1)
    clf.fit(iris.data, iris.target)
    score = clf.score(iris.data, iris.target)
    assert score > 0.9, "Failed with criterion %s and score = %f" % (criterion, score)

    clf = ForestClassifier(
        n_estimators=10, criterion=criterion, max_features=2, random_state=1
    )
    clf.fit(iris.data, iris.target)
    score = clf.score(iris.data, iris.target)
    assert score > 0.5, "Failed with criterion %s and score = %f" % (criterion, score)


@pytest.mark.parametrize("name", FOREST_REGRESSORS)
@pytest.mark.parametrize(
    "criterion", ("squared_error", "absolute_error", "friedman_mse")
)
def test_regression_criterion(name, criterion):
    # Check consistency on regression dataset.
    ForestRegressor = FOREST_REGRESSORS[name]

    reg = ForestRegressor(n_estimators=5, criterion=criterion, random_state=1)
    reg.fit(X_reg, y_reg)
    score = reg.score(X_reg, y_reg)
    assert score > 0.93, (
        "Failed with max_features=None, criterion %s and score = %f"
        % (
            criterion,
            score,
        )
    )

    reg = ForestRegressor(
        n_estimators=5, criterion=criterion, max_features=6, random_state=1
    )
    reg.fit(X_reg, y_reg)
    score = reg.score(X_reg, y_reg)
    assert score > 0.92, "Failed with max_features=6, criterion %s and score = %f" % (
        criterion,
        score,
    )


def test_poisson_vs_mse():
    """Test that random forest with poisson criterion performs better than
    mse for a poisson target.

    There is a similar test for DecisionTreeRegressor.
    """
    rng = np.random.RandomState(42)
    n_train, n_test, n_features = 500, 500, 10
    X = datasets.make_low_rank_matrix(
        n_samples=n_train + n_test, n_features=n_features, random_state=rng
    )
    #  We create a log-linear Poisson model and downscale coef as it will get
    # exponentiated.
    coef = rng.uniform(low=-2, high=2, size=n_features) / np.max(X, axis=0)
    y = rng.poisson(lam=np.exp(X @ coef))
    X_train, X_test, y_train, y_test = train_test_split(
        X, y, test_size=n_test, random_state=rng
    )
    # We prevent some overfitting by setting min_samples_split=10.
    forest_poi = RandomForestRegressor(
        criterion="poisson", min_samples_leaf=10, max_features="sqrt", random_state=rng
    )
    forest_mse = RandomForestRegressor(
        criterion="squared_error",
        min_samples_leaf=10,
        max_features="sqrt",
        random_state=rng,
    )

    forest_poi.fit(X_train, y_train)
    forest_mse.fit(X_train, y_train)
    dummy = DummyRegressor(strategy="mean").fit(X_train, y_train)

    for X, y, data_name in [(X_train, y_train, "train"), (X_test, y_test, "test")]:
        metric_poi = mean_poisson_deviance(y, forest_poi.predict(X))
        # squared_error forest might produce non-positive predictions => clip
        # If y = 0 for those, the poisson deviance gets too good.
        # If we drew more samples, we would eventually get y > 0 and the
        # poisson deviance would explode, i.e. be undefined. Therefore, we do
        # not clip to a tiny value like 1e-15, but to 1e-6. This acts like a
        # small penalty to the non-positive predictions.
        metric_mse = mean_poisson_deviance(
            y, np.clip(forest_mse.predict(X), 1e-6, None)
        )
        metric_dummy = mean_poisson_deviance(y, dummy.predict(X))
        # As squared_error might correctly predict 0 in train set, its train
        # score can be better than Poisson. This is no longer the case for the
        # test set. But keep the above comment for clipping in mind.
        if data_name == "test":
            assert metric_poi < metric_mse
        assert metric_poi < 0.8 * metric_dummy


@pytest.mark.parametrize("criterion", ("poisson", "squared_error"))
def test_balance_property_random_forest(criterion):
    """ "Test that sum(y_pred)==sum(y_true) on the training set."""
    rng = np.random.RandomState(42)
    n_train, n_test, n_features = 500, 500, 10
    X = datasets.make_low_rank_matrix(
        n_samples=n_train + n_test, n_features=n_features, random_state=rng
    )

    coef = rng.uniform(low=-2, high=2, size=n_features) / np.max(X, axis=0)
    y = rng.poisson(lam=np.exp(X @ coef))

    reg = RandomForestRegressor(
        criterion=criterion, n_estimators=10, bootstrap=False, random_state=rng
    )
    reg.fit(X, y)

    assert np.sum(reg.predict(X)) == pytest.approx(np.sum(y))


@pytest.mark.parametrize("name", FOREST_REGRESSORS)
def test_regressor_attributes(name):
    # Regression models should not have a classes_ attribute.
    r = FOREST_REGRESSORS[name](random_state=0)
    assert not hasattr(r, "classes_")
    assert not hasattr(r, "n_classes_")

    r.fit([[1, 2, 3], [4, 5, 6]], [1, 2])
    assert not hasattr(r, "classes_")
    assert not hasattr(r, "n_classes_")


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_probability(name):
    # Predict probabilities.
    ForestClassifier = FOREST_CLASSIFIERS[name]
    with np.errstate(divide="ignore"):
        clf = ForestClassifier(
            n_estimators=10, random_state=1, max_features=1, max_depth=1
        )
        clf.fit(iris.data, iris.target)
        assert_array_almost_equal(
            np.sum(clf.predict_proba(iris.data), axis=1), np.ones(iris.data.shape[0])
        )
        assert_array_almost_equal(
            clf.predict_proba(iris.data), np.exp(clf.predict_log_proba(iris.data))
        )


@pytest.mark.parametrize("dtype", (np.float64, np.float32))
@pytest.mark.parametrize(
    "name, criterion",
    itertools.chain(
        product(FOREST_CLASSIFIERS, ["gini", "log_loss"]),
        product(FOREST_REGRESSORS, ["squared_error", "friedman_mse", "absolute_error"]),
    ),
)
def test_importances(dtype, name, criterion):
    tolerance = 0.01
    if name in FOREST_REGRESSORS and criterion == "absolute_error":
        tolerance = 0.05

    # cast as dtype
    X = X_large.astype(dtype, copy=False)
    y = y_large.astype(dtype, copy=False)

    ForestEstimator = FOREST_ESTIMATORS[name]

    est = ForestEstimator(n_estimators=10, criterion=criterion, random_state=0)
    est.fit(X, y)
    importances = est.feature_importances_

    # The forest estimator can detect that only the first 3 features of the
    # dataset are informative:
    n_important = np.sum(importances > 0.1)
    assert importances.shape[0] == 10
    assert n_important == 3
    assert np.all(importances[:3] > 0.1)

    # Check with parallel
    importances = est.feature_importances_
    est.set_params(n_jobs=2)
    importances_parallel = est.feature_importances_
    assert_array_almost_equal(importances, importances_parallel)

    # Check with sample weights
    sample_weight = check_random_state(0).randint(1, 10, len(X))
    est = ForestEstimator(n_estimators=10, random_state=0, criterion=criterion)
    est.fit(X, y, sample_weight=sample_weight)
    importances = est.feature_importances_
    assert np.all(importances >= 0.0)

    for scale in [0.5, 100]:
        est = ForestEstimator(n_estimators=10, random_state=0, criterion=criterion)
        est.fit(X, y, sample_weight=scale * sample_weight)
        importances_bis = est.feature_importances_
        assert np.abs(importances - importances_bis).mean() < tolerance


def test_importances_asymptotic():
    # Check whether variable importances of totally randomized trees
    # converge towards their theoretical values (See Louppe et al,
    # Understanding variable importances in forests of randomized trees, 2013).

    def binomial(k, n):
        return 0 if k < 0 or k > n else comb(int(n), int(k), exact=True)

    def entropy(samples):
        n_samples = len(samples)
        entropy = 0.0

        for count in np.bincount(samples):
            p = 1.0 * count / n_samples
            if p > 0:
                entropy -= p * np.log2(p)

        return entropy

    def mdi_importance(X_m, X, y):
        n_samples, n_features = X.shape

        features = list(range(n_features))
        features.pop(X_m)
        values = [np.unique(X[:, i]) for i in range(n_features)]

        imp = 0.0

        for k in range(n_features):
            # Weight of each B of size k
            coef = 1.0 / (binomial(k, n_features) * (n_features - k))

            # For all B of size k
            for B in combinations(features, k):
                # For all values B=b
                for b in product(*[values[B[j]] for j in range(k)]):
                    mask_b = np.ones(n_samples, dtype=bool)

                    for j in range(k):
                        mask_b &= X[:, B[j]] == b[j]

                    X_, y_ = X[mask_b, :], y[mask_b]
                    n_samples_b = len(X_)

                    if n_samples_b > 0:
                        children = []

                        for xi in values[X_m]:
                            mask_xi = X_[:, X_m] == xi
                            children.append(y_[mask_xi])

                        imp += (
                            coef
                            * (1.0 * n_samples_b / n_samples)  # P(B=b)
                            * (
                                entropy(y_)
                                - sum(
                                    [
                                        entropy(c) * len(c) / n_samples_b
                                        for c in children
                                    ]
                                )
                            )
                        )

        return imp

    data = np.array(
        [
            [0, 0, 1, 0, 0, 1, 0, 1],
            [1, 0, 1, 1, 1, 0, 1, 2],
            [1, 0, 1, 1, 0, 1, 1, 3],
            [0, 1, 1, 1, 0, 1, 0, 4],
            [1, 1, 0, 1, 0, 1, 1, 5],
            [1, 1, 0, 1, 1, 1, 1, 6],
            [1, 0, 1, 0, 0, 1, 0, 7],
            [1, 1, 1, 1, 1, 1, 1, 8],
            [1, 1, 1, 1, 0, 1, 1, 9],
            [1, 1, 1, 0, 1, 1, 1, 0],
        ]
    )

    X, y = np.array(data[:, :7], dtype=bool), data[:, 7]
    n_features = X.shape[1]

    # Compute true importances
    true_importances = np.zeros(n_features)

    for i in range(n_features):
        true_importances[i] = mdi_importance(i, X, y)

    # Estimate importances with totally randomized trees
    clf = ExtraTreesClassifier(
        n_estimators=500, max_features=1, criterion="log_loss", random_state=0
    ).fit(X, y)

    importances = (
        sum(
            tree.tree_.compute_feature_importances(normalize=False)
            for tree in clf.estimators_
        )
        / clf.n_estimators
    )

    # Check correctness
    assert_almost_equal(entropy(y), sum(importances))
    assert np.abs(true_importances - importances).mean() < 0.01


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_unfitted_feature_importances(name):
    err_msg = (
        "This {} instance is not fitted yet. Call 'fit' with "
        "appropriate arguments before using this estimator.".format(name)
    )
    with pytest.raises(NotFittedError, match=err_msg):
        getattr(FOREST_ESTIMATORS[name](), "feature_importances_")


@pytest.mark.parametrize("ForestClassifier", FOREST_CLASSIFIERS.values())
@pytest.mark.parametrize("X_type", ["array", "sparse_csr", "sparse_csc"])
@pytest.mark.parametrize(
    "X, y, lower_bound_accuracy",
    [
        (
            *datasets.make_classification(n_samples=300, n_classes=2, random_state=0),
            0.9,
        ),
        (
            *datasets.make_classification(
                n_samples=1000, n_classes=3, n_informative=6, random_state=0
            ),
            0.65,
        ),
        (
            iris.data,
            iris.target * 2 + 1,
            0.65,
        ),
        (
            *datasets.make_multilabel_classification(n_samples=300, random_state=0),
            0.18,
        ),
    ],
)
@pytest.mark.parametrize("oob_score", [True, partial(f1_score, average="micro")])
def test_forest_classifier_oob(
    ForestClassifier, X, y, X_type, lower_bound_accuracy, oob_score
):
    """Check that OOB score is close to score on a test set."""
    X = _convert_container(X, constructor_name=X_type)
    X_train, X_test, y_train, y_test = train_test_split(
        X,
        y,
        test_size=0.5,
        random_state=0,
    )
    classifier = ForestClassifier(
        n_estimators=40,
        bootstrap=True,
        oob_score=oob_score,
        random_state=0,
    )

    assert not hasattr(classifier, "oob_score_")
    assert not hasattr(classifier, "oob_decision_function_")

    classifier.fit(X_train, y_train)
    if callable(oob_score):
        test_score = oob_score(y_test, classifier.predict(X_test))
    else:
        test_score = classifier.score(X_test, y_test)
        assert classifier.oob_score_ >= lower_bound_accuracy

    abs_diff = abs(test_score - classifier.oob_score_)
    assert abs_diff <= 0.11, f"{abs_diff=} is greater than 0.11"

    assert hasattr(classifier, "oob_score_")
    assert not hasattr(classifier, "oob_prediction_")
    assert hasattr(classifier, "oob_decision_function_")

    if y.ndim == 1:
        expected_shape = (X_train.shape[0], len(set(y)))
    else:
        expected_shape = (X_train.shape[0], len(set(y[:, 0])), y.shape[1])
    assert classifier.oob_decision_function_.shape == expected_shape


@pytest.mark.parametrize("ForestRegressor", FOREST_REGRESSORS.values())
@pytest.mark.parametrize("X_type", ["array", "sparse_csr", "sparse_csc"])
@pytest.mark.parametrize(
    "X, y, lower_bound_r2",
    [
        (
            *datasets.make_regression(
                n_samples=500, n_features=10, n_targets=1, random_state=0
            ),
            0.7,
        ),
        (
            *datasets.make_regression(
                n_samples=500, n_features=10, n_targets=2, random_state=0
            ),
            0.55,
        ),
    ],
)
@pytest.mark.parametrize("oob_score", [True, explained_variance_score])
def test_forest_regressor_oob(ForestRegressor, X, y, X_type, lower_bound_r2, oob_score):
    """Check that forest-based regressor provide an OOB score close to the
    score on a test set."""
    X = _convert_container(X, constructor_name=X_type)
    X_train, X_test, y_train, y_test = train_test_split(
        X,
        y,
        test_size=0.5,
        random_state=0,
    )
    regressor = ForestRegressor(
        n_estimators=50,
        bootstrap=True,
        oob_score=oob_score,
        random_state=0,
    )

    assert not hasattr(regressor, "oob_score_")
    assert not hasattr(regressor, "oob_prediction_")

    regressor.fit(X_train, y_train)
    if callable(oob_score):
        test_score = oob_score(y_test, regressor.predict(X_test))
    else:
        test_score = regressor.score(X_test, y_test)
        assert regressor.oob_score_ >= lower_bound_r2

    assert abs(test_score - regressor.oob_score_) <= 0.1

    assert hasattr(regressor, "oob_score_")
    assert hasattr(regressor, "oob_prediction_")
    assert not hasattr(regressor, "oob_decision_function_")

    if y.ndim == 1:
        expected_shape = (X_train.shape[0],)
    else:
        expected_shape = (X_train.shape[0], y.ndim)
    assert regressor.oob_prediction_.shape == expected_shape


@pytest.mark.parametrize("ForestEstimator", FOREST_CLASSIFIERS_REGRESSORS.values())
def test_forest_oob_warning(ForestEstimator):
    """Check that a warning is raised when not enough estimator and the OOB
    estimates will be inaccurate."""
    estimator = ForestEstimator(
        n_estimators=1,
        oob_score=True,
        bootstrap=True,
        random_state=0,
    )
    with pytest.warns(UserWarning, match="Some inputs do not have OOB scores"):
        estimator.fit(iris.data, iris.target)


@pytest.mark.parametrize("ForestEstimator", FOREST_CLASSIFIERS_REGRESSORS.values())
def test_forest_oob_score_requires_bootstrap(ForestEstimator):
    """Check that we raise an error if OOB score is requested without
    activating bootstrapping.
    """
    X = iris.data
    y = iris.target
    err_msg = "Out of bag estimation only available if bootstrap=True"
    estimator = ForestEstimator(oob_score=True, bootstrap=False)
    with pytest.raises(ValueError, match=err_msg):
        estimator.fit(X, y)


@pytest.mark.parametrize("ForestClassifier", FOREST_CLASSIFIERS.values())
def test_classifier_error_oob_score_multiclass_multioutput(ForestClassifier):
    """Check that we raise an error with when requesting OOB score with
    multiclass-multioutput classification target.
    """
    rng = np.random.RandomState(42)
    X = iris.data
    y = rng.randint(low=0, high=5, size=(iris.data.shape[0], 2))
    y_type = type_of_target(y)
    assert y_type == "multiclass-multioutput"
    estimator = ForestClassifier(oob_score=True, bootstrap=True)
    err_msg = "The type of target cannot be used to compute OOB estimates"
    with pytest.raises(ValueError, match=err_msg):
        estimator.fit(X, y)


@pytest.mark.parametrize("ForestRegressor", FOREST_REGRESSORS.values())
def test_forest_multioutput_integral_regression_target(ForestRegressor):
    """Check that multioutput regression with integral values is not interpreted
    as a multiclass-multioutput target and OOB score can be computed.
    """
    rng = np.random.RandomState(42)
    X = iris.data
    y = rng.randint(low=0, high=10, size=(iris.data.shape[0], 2))
    estimator = ForestRegressor(
        n_estimators=30, oob_score=True, bootstrap=True, random_state=0
    )
    estimator.fit(X, y)

    n_samples_bootstrap = _get_n_samples_bootstrap(len(X), estimator.max_samples)
    n_samples_test = X.shape[0] // 4
    oob_pred = np.zeros([n_samples_test, 2])
    for sample_idx, sample in enumerate(X[:n_samples_test]):
        n_samples_oob = 0
        oob_pred_sample = np.zeros(2)
        for tree in estimator.estimators_:
            oob_unsampled_indices = _generate_unsampled_indices(
                tree.random_state, len(X), n_samples_bootstrap
            )
            if sample_idx in oob_unsampled_indices:
                n_samples_oob += 1
                oob_pred_sample += tree.predict(sample.reshape(1, -1)).squeeze()
        oob_pred[sample_idx] = oob_pred_sample / n_samples_oob
    assert_allclose(oob_pred, estimator.oob_prediction_[:n_samples_test])


@pytest.mark.parametrize("oob_score", [True, False])
def test_random_trees_embedding_raise_error_oob(oob_score):
    with pytest.raises(TypeError, match="got an unexpected keyword argument"):
        RandomTreesEmbedding(oob_score=oob_score)
    with pytest.raises(NotImplementedError, match="OOB score not supported"):
        RandomTreesEmbedding()._set_oob_score_and_attributes(X, y)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_gridsearch(name):
    # Check that base trees can be grid-searched.
    forest = FOREST_CLASSIFIERS[name]()
    clf = GridSearchCV(forest, {"n_estimators": (1, 2), "max_depth": (1, 2)})
    clf.fit(iris.data, iris.target)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_parallel(name):
    """Check parallel computations in classification"""
    if name in FOREST_CLASSIFIERS:
        X = iris.data
        y = iris.target
    elif name in FOREST_REGRESSORS:
        X = X_reg
        y = y_reg

    ForestEstimator = FOREST_ESTIMATORS[name]
    forest = ForestEstimator(n_estimators=10, n_jobs=3, random_state=0)

    forest.fit(X, y)
    assert len(forest) == 10

    forest.set_params(n_jobs=1)
    y1 = forest.predict(X)
    forest.set_params(n_jobs=2)
    y2 = forest.predict(X)
    assert_array_almost_equal(y1, y2, 3)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_pickle(name):
    # Check pickability.
    if name in FOREST_CLASSIFIERS:
        X = iris.data[::2]
        y = iris.target[::2]
    elif name in FOREST_REGRESSORS:
        X = X_reg[::2]
        y = y_reg[::2]

    ForestEstimator = FOREST_ESTIMATORS[name]
    obj = ForestEstimator(random_state=0)
    obj.fit(X, y)
    score = obj.score(X, y)
    pickle_object = pickle.dumps(obj)

    obj2 = pickle.loads(pickle_object)
    assert type(obj2) == obj.__class__
    score2 = obj2.score(X, y)
    assert score == score2


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_multioutput(name):
    # Check estimators on multi-output problems.

    X_train = [
        [-2, -1],
        [-1, -1],
        [-1, -2],
        [1, 1],
        [1, 2],
        [2, 1],
        [-2, 1],
        [-1, 1],
        [-1, 2],
        [2, -1],
        [1, -1],
        [1, -2],
    ]
    y_train = [
        [-1, 0],
        [-1, 0],
        [-1, 0],
        [1, 1],
        [1, 1],
        [1, 1],
        [-1, 2],
        [-1, 2],
        [-1, 2],
        [1, 3],
        [1, 3],
        [1, 3],
    ]
    X_test = [[-1, -1], [1, 1], [-1, 1], [1, -1]]
    y_test = [[-1, 0], [1, 1], [-1, 2], [1, 3]]

    est = FOREST_ESTIMATORS[name](random_state=0, bootstrap=False)
    y_pred = est.fit(X_train, y_train).predict(X_test)
    assert_array_almost_equal(y_pred, y_test)

    if name in FOREST_CLASSIFIERS:
        with np.errstate(divide="ignore"):
            proba = est.predict_proba(X_test)
            assert len(proba) == 2
            assert proba[0].shape == (4, 2)
            assert proba[1].shape == (4, 4)

            log_proba = est.predict_log_proba(X_test)
            assert len(log_proba) == 2
            assert log_proba[0].shape == (4, 2)
            assert log_proba[1].shape == (4, 4)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_multioutput_string(name):
    # Check estimators on multi-output problems with string outputs.

    X_train = [
        [-2, -1],
        [-1, -1],
        [-1, -2],
        [1, 1],
        [1, 2],
        [2, 1],
        [-2, 1],
        [-1, 1],
        [-1, 2],
        [2, -1],
        [1, -1],
        [1, -2],
    ]
    y_train = [
        ["red", "blue"],
        ["red", "blue"],
        ["red", "blue"],
        ["green", "green"],
        ["green", "green"],
        ["green", "green"],
        ["red", "purple"],
        ["red", "purple"],
        ["red", "purple"],
        ["green", "yellow"],
        ["green", "yellow"],
        ["green", "yellow"],
    ]
    X_test = [[-1, -1], [1, 1], [-1, 1], [1, -1]]
    y_test = [
        ["red", "blue"],
        ["green", "green"],
        ["red", "purple"],
        ["green", "yellow"],
    ]

    est = FOREST_ESTIMATORS[name](random_state=0, bootstrap=False)
    y_pred = est.fit(X_train, y_train).predict(X_test)
    assert_array_equal(y_pred, y_test)

    with np.errstate(divide="ignore"):
        proba = est.predict_proba(X_test)
        assert len(proba) == 2
        assert proba[0].shape == (4, 2)
        assert proba[1].shape == (4, 4)

        log_proba = est.predict_log_proba(X_test)
        assert len(log_proba) == 2
        assert log_proba[0].shape == (4, 2)
        assert log_proba[1].shape == (4, 4)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_classes_shape(name):
    # Test that n_classes_ and classes_ have proper shape.
    ForestClassifier = FOREST_CLASSIFIERS[name]

    # Classification, single output
    clf = ForestClassifier(random_state=0).fit(X, y)

    assert clf.n_classes_ == 2
    assert_array_equal(clf.classes_, [-1, 1])

    # Classification, multi-output
    _y = np.vstack((y, np.array(y) * 2)).T
    clf = ForestClassifier(random_state=0).fit(X, _y)

    assert_array_equal(clf.n_classes_, [2, 2])
    assert_array_equal(clf.classes_, [[-1, 1], [-2, 2]])


def test_random_trees_dense_type():
    # Test that the `sparse_output` parameter of RandomTreesEmbedding
    # works by returning a dense array.

    # Create the RTE with sparse=False
    hasher = RandomTreesEmbedding(n_estimators=10, sparse_output=False)
    X, y = datasets.make_circles(factor=0.5)
    X_transformed = hasher.fit_transform(X)

    # Assert that type is ndarray, not scipy.sparse.csr_matrix
    assert isinstance(X_transformed, np.ndarray)


def test_random_trees_dense_equal():
    # Test that the `sparse_output` parameter of RandomTreesEmbedding
    # works by returning the same array for both argument values.

    # Create the RTEs
    hasher_dense = RandomTreesEmbedding(
        n_estimators=10, sparse_output=False, random_state=0
    )
    hasher_sparse = RandomTreesEmbedding(
        n_estimators=10, sparse_output=True, random_state=0
    )
    X, y = datasets.make_circles(factor=0.5)
    X_transformed_dense = hasher_dense.fit_transform(X)
    X_transformed_sparse = hasher_sparse.fit_transform(X)

    # Assert that dense and sparse hashers have same array.
    assert_array_equal(X_transformed_sparse.toarray(), X_transformed_dense)


def test_random_hasher():
    # test random forest hashing on circles dataset
    # make sure that it is linearly separable.
    # even after projected to two SVD dimensions
    # Note: Not all random_states produce perfect results.
    hasher = RandomTreesEmbedding(n_estimators=30, random_state=1)
    X, y = datasets.make_circles(factor=0.5)
    X_transformed = hasher.fit_transform(X)

    # test fit and transform:
    hasher = RandomTreesEmbedding(n_estimators=30, random_state=1)
    assert_array_equal(hasher.fit(X).transform(X).toarray(), X_transformed.toarray())

    # one leaf active per data point per forest
    assert X_transformed.shape[0] == X.shape[0]
    assert_array_equal(X_transformed.sum(axis=1), hasher.n_estimators)
    svd = TruncatedSVD(n_components=2)
    X_reduced = svd.fit_transform(X_transformed)
    linear_clf = LinearSVC()
    linear_clf.fit(X_reduced, y)
    assert linear_clf.score(X_reduced, y) == 1.0


@pytest.mark.parametrize("csc_container", CSC_CONTAINERS)
def test_random_hasher_sparse_data(csc_container):
    X, y = datasets.make_multilabel_classification(random_state=0)
    hasher = RandomTreesEmbedding(n_estimators=30, random_state=1)
    X_transformed = hasher.fit_transform(X)
    X_transformed_sparse = hasher.fit_transform(csc_container(X))
    assert_array_equal(X_transformed_sparse.toarray(), X_transformed.toarray())


def test_parallel_train():
    rng = check_random_state(12321)
    n_samples, n_features = 80, 30
    X_train = rng.randn(n_samples, n_features)
    y_train = rng.randint(0, 2, n_samples)

    clfs = [
        RandomForestClassifier(n_estimators=20, n_jobs=n_jobs, random_state=12345).fit(
            X_train, y_train
        )
        for n_jobs in [1, 2, 3, 8, 16, 32]
    ]

    X_test = rng.randn(n_samples, n_features)
    probas = [clf.predict_proba(X_test) for clf in clfs]
    for proba1, proba2 in itertools.pairwise(probas):
        assert_array_almost_equal(proba1, proba2)


def test_distribution():
    rng = check_random_state(12321)

    # Single variable with 4 values
    X = rng.randint(0, 4, size=(1000, 1))
    y = rng.rand(1000)
    n_trees = 500

    reg = ExtraTreesRegressor(n_estimators=n_trees, random_state=42).fit(X, y)

    uniques = defaultdict(int)
    for tree in reg.estimators_:
        tree = "".join(
            ("%d,%d/" % (f, int(t)) if f >= 0 else "-")
            for f, t in zip(tree.tree_.feature, tree.tree_.threshold)
        )

        uniques[tree] += 1

    uniques = sorted([(1.0 * count / n_trees, tree) for tree, count in uniques.items()])

    # On a single variable problem where X_0 has 4 equiprobable values, there
    # are 5 ways to build a random tree. The more compact (0,1/0,0/--0,2/--) of
    # them has probability 1/3 while the 4 others have probability 1/6.

    assert len(uniques) == 5
    assert 0.20 > uniques[0][0]  # Rough approximation of 1/6.
    assert 0.20 > uniques[1][0]
    assert 0.20 > uniques[2][0]
    assert 0.20 > uniques[3][0]
    assert uniques[4][0] > 0.3
    assert uniques[4][1] == "0,1/0,0/--0,2/--"

    # Two variables, one with 2 values, one with 3 values
    X = np.empty((1000, 2))
    X[:, 0] = np.random.randint(0, 2, 1000)
    X[:, 1] = np.random.randint(0, 3, 1000)
    y = rng.rand(1000)

    reg = ExtraTreesRegressor(max_features=1, random_state=1).fit(X, y)

    uniques = defaultdict(int)
    for tree in reg.estimators_:
        tree = "".join(
            ("%d,%d/" % (f, int(t)) if f >= 0 else "-")
            for f, t in zip(tree.tree_.feature, tree.tree_.threshold)
        )

        uniques[tree] += 1

    uniques = [(count, tree) for tree, count in uniques.items()]
    assert len(uniques) == 8


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_max_leaf_nodes_max_depth(name):
    X, y = hastie_X, hastie_y

    # Test precedence of max_leaf_nodes over max_depth.
    ForestEstimator = FOREST_ESTIMATORS[name]
    est = ForestEstimator(
        max_depth=1, max_leaf_nodes=4, n_estimators=1, random_state=0
    ).fit(X, y)
    assert est.estimators_[0].get_depth() == 1

    est = ForestEstimator(max_depth=1, n_estimators=1, random_state=0).fit(X, y)
    assert est.estimators_[0].get_depth() == 1


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_min_samples_split(name):
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]

    est = ForestEstimator(min_samples_split=10, n_estimators=1, random_state=0)
    est.fit(X, y)
    node_idx = est.estimators_[0].tree_.children_left != -1
    node_samples = est.estimators_[0].tree_.n_node_samples[node_idx]

    assert np.min(node_samples) > len(X) * 0.5 - 1, "Failed with {0}".format(name)

    est = ForestEstimator(min_samples_split=0.5, n_estimators=1, random_state=0)
    est.fit(X, y)
    node_idx = est.estimators_[0].tree_.children_left != -1
    node_samples = est.estimators_[0].tree_.n_node_samples[node_idx]

    assert np.min(node_samples) > len(X) * 0.5 - 1, "Failed with {0}".format(name)


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_min_samples_leaf(name):
    X, y = hastie_X, hastie_y

    # Test if leaves contain more than leaf_count training examples
    ForestEstimator = FOREST_ESTIMATORS[name]

    est = ForestEstimator(min_samples_leaf=5, n_estimators=1, random_state=0)
    est.fit(X, y)
    out = est.estimators_[0].tree_.apply(X)
    node_counts = np.bincount(out)
    # drop inner nodes
    leaf_count = node_counts[node_counts != 0]
    assert np.min(leaf_count) > 4, "Failed with {0}".format(name)

    est = ForestEstimator(min_samples_leaf=0.25, n_estimators=1, random_state=0)
    est.fit(X, y)
    out = est.estimators_[0].tree_.apply(X)
    node_counts = np.bincount(out)
    # drop inner nodes
    leaf_count = node_counts[node_counts != 0]
    assert np.min(leaf_count) > len(X) * 0.25 - 1, "Failed with {0}".format(name)


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_min_weight_fraction_leaf(name):
    X, y = hastie_X, hastie_y

    # Test if leaves contain at least min_weight_fraction_leaf of the
    # training set
    ForestEstimator = FOREST_ESTIMATORS[name]
    rng = np.random.RandomState(0)
    weights = rng.rand(X.shape[0])
    total_weight = np.sum(weights)

    # test both DepthFirstTreeBuilder and BestFirstTreeBuilder
    # by setting max_leaf_nodes
    for frac in np.linspace(0, 0.5, 6):
        est = ForestEstimator(
            min_weight_fraction_leaf=frac, n_estimators=1, random_state=0
        )
        if "RandomForest" in name:
            est.bootstrap = False

        est.fit(X, y, sample_weight=weights)
        out = est.estimators_[0].tree_.apply(X)
        node_weights = np.bincount(out, weights=weights)
        # drop inner nodes
        leaf_weights = node_weights[node_weights != 0]
        assert np.min(leaf_weights) >= total_weight * est.min_weight_fraction_leaf, (
            "Failed with {0} min_weight_fraction_leaf={1}".format(
                name, est.min_weight_fraction_leaf
            )
        )


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
@pytest.mark.parametrize(
    "sparse_container", COO_CONTAINERS + CSC_CONTAINERS + CSR_CONTAINERS
)
def test_sparse_input(name, sparse_container):
    X, y = datasets.make_multilabel_classification(random_state=0, n_samples=50)

    ForestEstimator = FOREST_ESTIMATORS[name]

    dense = ForestEstimator(random_state=0, max_depth=2).fit(X, y)
    sparse = ForestEstimator(random_state=0, max_depth=2).fit(sparse_container(X), y)

    assert_array_almost_equal(sparse.apply(X), dense.apply(X))

    if name in FOREST_CLASSIFIERS or name in FOREST_REGRESSORS:
        assert_array_almost_equal(sparse.predict(X), dense.predict(X))
        assert_array_almost_equal(
            sparse.feature_importances_, dense.feature_importances_
        )

    if name in FOREST_CLASSIFIERS:
        assert_array_almost_equal(sparse.predict_proba(X), dense.predict_proba(X))
        assert_array_almost_equal(
            sparse.predict_log_proba(X), dense.predict_log_proba(X)
        )

    if name in FOREST_TRANSFORMERS:
        assert_array_almost_equal(
            sparse.transform(X).toarray(), dense.transform(X).toarray()
        )
        assert_array_almost_equal(
            sparse.fit_transform(X).toarray(), dense.fit_transform(X).toarray()
        )


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
@pytest.mark.parametrize("dtype", (np.float64, np.float32))
def test_memory_layout(name, dtype):
    # Test that it works no matter the memory layout
    est = FOREST_ESTIMATORS[name](random_state=0, bootstrap=False)

    # Dense
    for container, kwargs in (
        (np.asarray, {}),  # Nothing
        (np.asarray, {"order": "C"}),  # C-order
        (np.asarray, {"order": "F"}),  # F-order
        (np.ascontiguousarray, {}),  # Contiguous
    ):
        X = container(iris.data, dtype=dtype, **kwargs)
        y = iris.target
        assert_array_almost_equal(est.fit(X, y).predict(X), y)

    # Sparse (if applicable)
    if est.estimator.splitter in SPARSE_SPLITTERS:
        for sparse_container in COO_CONTAINERS + CSC_CONTAINERS + CSR_CONTAINERS:
            X = sparse_container(iris.data, dtype=dtype)
            y = iris.target
            assert_array_almost_equal(est.fit(X, y).predict(X), y)

    # Strided
    X = np.asarray(iris.data[::3], dtype=dtype)
    y = iris.target[::3]
    assert_array_almost_equal(est.fit(X, y).predict(X), y)


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_1d_input(name):
    X = iris.data[:, 0]
    X_2d = iris.data[:, 0].reshape((-1, 1))
    y = iris.target

    with ignore_warnings():
        ForestEstimator = FOREST_ESTIMATORS[name]
        with pytest.raises(ValueError):
            ForestEstimator(n_estimators=1, random_state=0).fit(X, y)

        est = ForestEstimator(random_state=0)
        est.fit(X_2d, y)

        if name in FOREST_CLASSIFIERS or name in FOREST_REGRESSORS:
            with pytest.raises(ValueError):
                est.predict(X)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_class_weights(name):
    # Check class_weights resemble sample_weights behavior.
    ForestClassifier = FOREST_CLASSIFIERS[name]

    # Iris is balanced, so no effect expected for using 'balanced' weights
    clf1 = ForestClassifier(random_state=0)
    clf1.fit(iris.data, iris.target)
    clf2 = ForestClassifier(class_weight="balanced", random_state=0)
    clf2.fit(iris.data, iris.target)
    assert_almost_equal(clf1.feature_importances_, clf2.feature_importances_)

    # Make a multi-output problem with three copies of Iris
    iris_multi = np.vstack((iris.target, iris.target, iris.target)).T
    # Create user-defined weights that should balance over the outputs
    clf3 = ForestClassifier(
        class_weight=[
            {0: 2.0, 1: 2.0, 2: 1.0},
            {0: 2.0, 1: 1.0, 2: 2.0},
            {0: 1.0, 1: 2.0, 2: 2.0},
        ],
        random_state=0,
    )
    clf3.fit(iris.data, iris_multi)
    assert_almost_equal(clf2.feature_importances_, clf3.feature_importances_)
    # Check against multi-output "balanced" which should also have no effect
    clf4 = ForestClassifier(class_weight="balanced", random_state=0)
    clf4.fit(iris.data, iris_multi)
    assert_almost_equal(clf3.feature_importances_, clf4.feature_importances_)

    # Inflate importance of class 1, check against user-defined weights
    sample_weight = np.ones(iris.target.shape)
    sample_weight[iris.target == 1] *= 100
    class_weight = {0: 1.0, 1: 100.0, 2: 1.0}
    clf1 = ForestClassifier(random_state=0)
    clf1.fit(iris.data, iris.target, sample_weight)
    clf2 = ForestClassifier(class_weight=class_weight, random_state=0)
    clf2.fit(iris.data, iris.target)
    assert_almost_equal(clf1.feature_importances_, clf2.feature_importances_)

    # Check that sample_weight and class_weight are multiplicative
    clf1 = ForestClassifier(random_state=0)
    clf1.fit(iris.data, iris.target, sample_weight**2)
    clf2 = ForestClassifier(class_weight=class_weight, random_state=0)
    clf2.fit(iris.data, iris.target, sample_weight)
    assert_almost_equal(clf1.feature_importances_, clf2.feature_importances_)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_class_weight_balanced_and_bootstrap_multi_output(name):
    # Test class_weight works for multi-output"""
    ForestClassifier = FOREST_CLASSIFIERS[name]
    _y = np.vstack((y, np.array(y) * 2)).T
    clf = ForestClassifier(class_weight="balanced", random_state=0)
    clf.fit(X, _y)
    clf = ForestClassifier(
        class_weight=[{-1: 0.5, 1: 1.0}, {-2: 1.0, 2: 1.0}], random_state=0
    )
    clf.fit(X, _y)
    # smoke test for balanced subsample
    clf = ForestClassifier(class_weight="balanced_subsample", random_state=0)
    clf.fit(X, _y)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_class_weight_errors(name):
    # Test if class_weight raises errors and warnings when expected.
    ForestClassifier = FOREST_CLASSIFIERS[name]
    _y = np.vstack((y, np.array(y) * 2)).T

    # Warning warm_start with preset
    clf = ForestClassifier(class_weight="balanced", warm_start=True, random_state=0)
    clf.fit(X, y)

    warn_msg = (
        "Warm-start fitting without increasing n_estimators does not fit new trees."
    )
    with pytest.warns(UserWarning, match=warn_msg):
        clf.fit(X, _y)

    # Incorrect length list for multi-output
    clf = ForestClassifier(class_weight=[{-1: 0.5, 1: 1.0}], random_state=0)
    with pytest.raises(ValueError):
        clf.fit(X, _y)


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_warm_start(name):
    # Test if fitting incrementally with warm start gives a forest of the
    # right size and the same results as a normal fit.
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]
    est_ws = None
    for n_estimators in [5, 10]:
        if est_ws is None:
            est_ws = ForestEstimator(
                n_estimators=n_estimators, random_state=42, warm_start=True
            )
        else:
            est_ws.set_params(n_estimators=n_estimators)
        est_ws.fit(X, y)
        assert len(est_ws) == n_estimators

    est_no_ws = ForestEstimator(n_estimators=10, random_state=42, warm_start=False)
    est_no_ws.fit(X, y)

    assert set([tree.random_state for tree in est_ws]) == set(
        [tree.random_state for tree in est_no_ws]
    )

    assert_array_equal(
        est_ws.apply(X), est_no_ws.apply(X), err_msg="Failed with {0}".format(name)
    )


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_warm_start_clear(name):
    # Test if fit clears state and grows a new forest when warm_start==False.
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]
    est = ForestEstimator(n_estimators=5, max_depth=1, warm_start=False, random_state=1)
    est.fit(X, y)

    est_2 = ForestEstimator(
        n_estimators=5, max_depth=1, warm_start=True, random_state=2
    )
    est_2.fit(X, y)  # inits state
    est_2.set_params(warm_start=False, random_state=1)
    est_2.fit(X, y)  # clears old state and equals est

    assert_array_almost_equal(est_2.apply(X), est.apply(X))


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_warm_start_smaller_n_estimators(name):
    # Test if warm start second fit with smaller n_estimators raises error.
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]
    est = ForestEstimator(n_estimators=5, max_depth=1, warm_start=True)
    est.fit(X, y)
    est.set_params(n_estimators=4)
    with pytest.raises(ValueError):
        est.fit(X, y)


@pytest.mark.parametrize("name", FOREST_ESTIMATORS)
def test_warm_start_equal_n_estimators(name):
    # Test if warm start with equal n_estimators does nothing and returns the
    # same forest and raises a warning.
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]
    est = ForestEstimator(n_estimators=5, max_depth=3, warm_start=True, random_state=1)
    est.fit(X, y)

    est_2 = ForestEstimator(
        n_estimators=5, max_depth=3, warm_start=True, random_state=1
    )
    est_2.fit(X, y)
    # Now est_2 equals est.

    est_2.set_params(random_state=2)
    warn_msg = (
        "Warm-start fitting without increasing n_estimators does not fit new trees."
    )
    with pytest.warns(UserWarning, match=warn_msg):
        est_2.fit(X, y)
    # If we had fit the trees again we would have got a different forest as we
    # changed the random state.
    assert_array_equal(est.apply(X), est_2.apply(X))


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_warm_start_oob(name):
    # Test that the warm start computes oob score when asked.
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]
    # Use 15 estimators to avoid 'some inputs do not have OOB scores' warning.
    est = ForestEstimator(
        n_estimators=15,
        max_depth=3,
        warm_start=False,
        random_state=1,
        bootstrap=True,
        oob_score=True,
    )
    est.fit(X, y)

    est_2 = ForestEstimator(
        n_estimators=5,
        max_depth=3,
        warm_start=False,
        random_state=1,
        bootstrap=True,
        oob_score=False,
    )
    est_2.fit(X, y)

    est_2.set_params(warm_start=True, oob_score=True, n_estimators=15)
    est_2.fit(X, y)

    assert hasattr(est_2, "oob_score_")
    assert est.oob_score_ == est_2.oob_score_

    # Test that oob_score is computed even if we don't need to train
    # additional trees.
    est_3 = ForestEstimator(
        n_estimators=15,
        max_depth=3,
        warm_start=True,
        random_state=1,
        bootstrap=True,
        oob_score=False,
    )
    est_3.fit(X, y)
    assert not hasattr(est_3, "oob_score_")

    est_3.set_params(oob_score=True)
    ignore_warnings(est_3.fit)(X, y)

    assert est.oob_score_ == est_3.oob_score_


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_oob_not_computed_twice(name):
    # Check that oob_score is not computed twice when warm_start=True.
    X, y = hastie_X, hastie_y
    ForestEstimator = FOREST_ESTIMATORS[name]

    est = ForestEstimator(
        n_estimators=10, warm_start=True, bootstrap=True, oob_score=True
    )

    with patch.object(
        est, "_set_oob_score_and_attributes", wraps=est._set_oob_score_and_attributes
    ) as mock_set_oob_score_and_attributes:
        est.fit(X, y)

        with pytest.warns(UserWarning, match="Warm-start fitting without increasing"):
            est.fit(X, y)

        mock_set_oob_score_and_attributes.assert_called_once()


def test_dtype_convert(n_classes=15):
    classifier = RandomForestClassifier(random_state=0, bootstrap=False)

    X = np.eye(n_classes)
    y = [ch for ch in "ABCDEFGHIJKLMNOPQRSTU"[:n_classes]]

    result = classifier.fit(X, y).predict(X)
    assert_array_equal(classifier.classes_, y)
    assert_array_equal(result, y)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_decision_path(name):
    X, y = hastie_X, hastie_y
    n_samples = X.shape[0]
    ForestEstimator = FOREST_ESTIMATORS[name]
    est = ForestEstimator(n_estimators=5, max_depth=1, warm_start=False, random_state=1)
    est.fit(X, y)
    indicator, n_nodes_ptr = est.decision_path(X)

    assert indicator.shape[1] == n_nodes_ptr[-1]
    assert indicator.shape[0] == n_samples
    assert_array_equal(
        np.diff(n_nodes_ptr), [e.tree_.node_count for e in est.estimators_]
    )

    # Assert that leaves index are correct
    leaves = est.apply(X)
    for est_id in range(leaves.shape[1]):
        leave_indicator = [
            indicator[i, n_nodes_ptr[est_id] + j]
            for i, j in enumerate(leaves[:, est_id])
        ]
        assert_array_almost_equal(leave_indicator, np.ones(shape=n_samples))


def test_min_impurity_decrease():
    X, y = datasets.make_hastie_10_2(n_samples=100, random_state=1)
    all_estimators = [
        RandomForestClassifier,
        RandomForestRegressor,
        ExtraTreesClassifier,
        ExtraTreesRegressor,
    ]

    for Estimator in all_estimators:
        est = Estimator(min_impurity_decrease=0.1)
        est.fit(X, y)
        for tree in est.estimators_:
            # Simply check if the parameter is passed on correctly. Tree tests
            # will suffice for the actual working of this param
            assert tree.min_impurity_decrease == 0.1


def test_poisson_y_positive_check():
    est = RandomForestRegressor(criterion="poisson")
    X = np.zeros((3, 3))

    y = [-1, 1, 3]
    err_msg = (
        r"Some value\(s\) of y are negative which is "
        r"not allowed for Poisson regression."
    )
    with pytest.raises(ValueError, match=err_msg):
        est.fit(X, y)

    y = [0, 0, 0]
    err_msg = (
        r"Sum of y is not strictly positive which "
        r"is necessary for Poisson regression."
    )
    with pytest.raises(ValueError, match=err_msg):
        est.fit(X, y)


# mypy error: Variable "DEFAULT_JOBLIB_BACKEND" is not valid type
class MyBackend(DEFAULT_JOBLIB_BACKEND):  # type: ignore[valid-type,misc]
    def __init__(self, *args, **kwargs):
        self.count = 0
        super().__init__(*args, **kwargs)

    def start_call(self):
        self.count += 1
        return super().start_call()


joblib.register_parallel_backend("testing", MyBackend)


# TODO: remove mark once loky bug is fixed:
# https://github.com/joblib/loky/issues/458
@pytest.mark.thread_unsafe
@skip_if_no_parallel
def test_backend_respected():
    clf = RandomForestClassifier(n_estimators=10, n_jobs=2)

    with joblib.parallel_backend("testing") as (ba, n_jobs):
        clf.fit(X, y)

    assert ba.count > 0

    # predict_proba requires shared memory. Ensure that's honored.
    with joblib.parallel_backend("testing") as (ba, _):
        clf.predict_proba(X)

    assert ba.count == 0


def test_forest_feature_importances_sum():
    X, y = make_classification(
        n_samples=15, n_informative=3, random_state=1, n_classes=3
    )
    clf = RandomForestClassifier(
        min_samples_leaf=5, random_state=42, n_estimators=200
    ).fit(X, y)
    assert math.isclose(1, clf.feature_importances_.sum(), abs_tol=1e-7)


def test_forest_degenerate_feature_importances():
    # build a forest of single node trees. See #13636
    X = np.zeros((10, 10))
    y = np.ones((10,))
    gbr = RandomForestRegressor(n_estimators=10).fit(X, y)
    assert_array_equal(gbr.feature_importances_, np.zeros(10, dtype=np.float64))


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_max_samples_bootstrap(name):
    # Check invalid `max_samples` values
    est = FOREST_CLASSIFIERS_REGRESSORS[name](bootstrap=False, max_samples=0.5)
    err_msg = (
        r"`max_sample` cannot be set if `bootstrap=False`. "
        r"Either switch to `bootstrap=True` or set "
        r"`max_sample=None`."
    )
    with pytest.raises(ValueError, match=err_msg):
        est.fit(X, y)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS_REGRESSORS)
def test_large_max_samples_exception(name):
    # Check invalid `max_samples`
    est = FOREST_CLASSIFIERS_REGRESSORS[name](bootstrap=True, max_samples=int(1e9))
    match = "`max_samples` must be <= n_samples=6 but got value 1000000000"
    with pytest.raises(ValueError, match=match):
        est.fit(X, y)


@pytest.mark.parametrize("name", FOREST_REGRESSORS)
def test_max_samples_boundary_regressors(name):
    X_train, X_test, y_train, y_test = train_test_split(
        X_reg, y_reg, train_size=0.7, test_size=0.3, random_state=0
    )

    ms_1_model = FOREST_REGRESSORS[name](
        bootstrap=True, max_samples=1.0, random_state=0
    )
    ms_1_predict = ms_1_model.fit(X_train, y_train).predict(X_test)

    ms_None_model = FOREST_REGRESSORS[name](
        bootstrap=True, max_samples=None, random_state=0
    )
    ms_None_predict = ms_None_model.fit(X_train, y_train).predict(X_test)

    ms_1_ms = mean_squared_error(ms_1_predict, y_test)
    ms_None_ms = mean_squared_error(ms_None_predict, y_test)

    assert ms_1_ms == pytest.approx(ms_None_ms)


@pytest.mark.parametrize("name", FOREST_CLASSIFIERS)
def test_max_samples_boundary_classifiers(name):
    X_train, X_test, y_train, _ = train_test_split(
        X_large, y_large, random_state=0, stratify=y_large
    )

    ms_1_model = FOREST_CLASSIFIERS[name](
        bootstrap=True, max_samples=1.0, random_state=0
    )
    ms_1_proba = ms_1_model.fit(X_train, y_train).predict_proba(X_test)

    ms_None_model = FOREST_CLASSIFIERS[name](
        bootstrap=True, max_samples=None, random_state=0
    )
    ms_None_proba = ms_None_model.fit(X_train, y_train).predict_proba(X_test)

    np.testing.assert_allclose(ms_1_proba, ms_None_proba)


@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_forest_y_sparse(csr_container):
    X = [[1, 2, 3]]
    y = csr_container([[4, 5, 6]])
    est = RandomForestClassifier()
    msg = "sparse multilabel-indicator for y is not supported."
    with pytest.raises(ValueError, match=msg):
        est.fit(X, y)


@pytest.mark.parametrize("ForestClass", [RandomForestClassifier, RandomForestRegressor])
def test_little_tree_with_small_max_samples(ForestClass):
    rng = np.random.RandomState(1)

    X = rng.randn(10000, 2)
    y = rng.randn(10000) > 0

    # First fit with no restriction on max samples
    est1 = ForestClass(
        n_estimators=1,
        random_state=rng,
        max_samples=None,
    )

    # Second fit with max samples restricted to just 2
    est2 = ForestClass(
        n_estimators=1,
        random_state=rng,
        max_samples=2,
    )

    est1.fit(X, y)
    est2.fit(X, y)

    tree1 = est1.estimators_[0].tree_
    tree2 = est2.estimators_[0].tree_

    msg = "Tree without `max_samples` restriction should have more nodes"
    assert tree1.node_count > tree2.node_count, msg


@pytest.mark.parametrize("Forest", FOREST_REGRESSORS)
def test_mse_criterion_object_segfault_smoke_test(Forest):
    # This is a smoke test to ensure that passing a mutable criterion
    # does not cause a segfault when fitting with concurrent threads.
    # Non-regression test for:
    # https://github.com/scikit-learn/scikit-learn/issues/12623
    from sklearn.tree._criterion import MSE

    y = y_reg.reshape(-1, 1)
    n_samples, n_outputs = y.shape
    mse_criterion = MSE(n_outputs, n_samples)
    est = FOREST_REGRESSORS[Forest](n_estimators=2, n_jobs=2, criterion=mse_criterion)

    est.fit(X_reg, y)


def test_random_trees_embedding_feature_names_out():
    """Check feature names out for Random Trees Embedding."""
    random_state = np.random.RandomState(0)
    X = np.abs(random_state.randn(100, 4))
    hasher = RandomTreesEmbedding(
        n_estimators=2, max_depth=2, sparse_output=False, random_state=0
    ).fit(X)
    names = hasher.get_feature_names_out()
    expected_names = [
        f"randomtreesembedding_{tree}_{leaf}"
        # Note: nodes with indices 0, 1 and 4 are internal split nodes and
        # therefore do not appear in the expected output feature names.
        for tree, leaf in [
            (0, 2),
            (0, 3),
            (0, 5),
            (0, 6),
            (1, 2),
            (1, 3),
            (1, 5),
            (1, 6),
        ]
    ]
    assert_array_equal(expected_names, names)


@pytest.mark.parametrize("csr_container", CSR_CONTAINERS)
def test_read_only_buffer(csr_container, monkeypatch):
    """RandomForestClassifier must work on readonly sparse data.

    Non-regression test for: https://github.com/scikit-learn/scikit-learn/issues/25333
    """
    monkeypatch.setattr(
        sklearn.ensemble._forest,
        "Parallel",
        partial(Parallel, max_nbytes=100),
    )
    rng = np.random.RandomState(seed=0)

    X, y = make_classification(n_samples=100, n_features=200, random_state=rng)
    X = csr_container(X, copy=True)

    clf = RandomForestClassifier(n_jobs=2, random_state=rng)
    cross_val_score(clf, X, y, cv=2)


@pytest.mark.parametrize("class_weight", ["balanced_subsample", None])
def test_round_samples_to_one_when_samples_too_low(class_weight):
    """Check low max_samples works and is rounded to one.

    Non-regression test for gh-24037.
    """
    X, y = datasets.load_wine(return_X_y=True)
    forest = RandomForestClassifier(
        n_estimators=10, max_samples=1e-4, class_weight=class_weight, random_state=0
    )
    forest.fit(X, y)


@pytest.mark.parametrize("seed", [None, 1])
@pytest.mark.parametrize("bootstrap", [True, False])
@pytest.mark.parametrize("ForestClass", FOREST_CLASSIFIERS_REGRESSORS.values())
def test_estimators_samples(ForestClass, bootstrap, seed):
    """Estimators_samples_ property should be consistent.

    Tests consistency across fits and whether or not the seed for the random generator
    is set.
    """
    X, y = make_hastie_10_2(n_samples=200, random_state=1)

    if bootstrap:
        max_samples = 0.5
    else:
        max_samples = None
    est = ForestClass(
        n_estimators=10,
        max_samples=max_samples,
        max_features=0.5,
        random_state=seed,
        bootstrap=bootstrap,
    )
    est.fit(X, y)

    estimators_samples = est.estimators_samples_.copy()

    # Test repeated calls result in same set of indices
    assert_array_equal(estimators_samples, est.estimators_samples_)
    estimators = est.estimators_

    assert isinstance(estimators_samples, list)
    assert len(estimators_samples) == len(estimators)
    assert estimators_samples[0].dtype == np.int32

    for i in range(len(estimators)):
        if bootstrap:
            assert len(estimators_samples[i]) == len(X) // 2

            # the bootstrap should be a resampling with replacement
            assert len(np.unique(estimators_samples[i])) < len(estimators_samples[i])
        else:
            assert len(set(estimators_samples[i])) == len(X)

    estimator_index = 0
    estimator_samples = estimators_samples[estimator_index]
    estimator = estimators[estimator_index]

    X_train = X[estimator_samples]
    y_train = y[estimator_samples]

    orig_tree_values = estimator.tree_.value
    estimator = clone(estimator)
    estimator.fit(X_train, y_train)
    new_tree_values = estimator.tree_.value
    assert_allclose(orig_tree_values, new_tree_values)


@pytest.mark.parametrize(
    "make_data, Forest",
    [
        (datasets.make_regression, RandomForestRegressor),
        (datasets.make_classification, RandomForestClassifier),
        (datasets.make_regression, ExtraTreesRegressor),
        (datasets.make_classification, ExtraTreesClassifier),
    ],
)
def test_missing_values_is_resilient(make_data, Forest):
    """Check that forest can deal with missing values and has decent performance."""

    rng = np.random.RandomState(0)
    n_samples, n_features = 1000, 10
    X, y = make_data(n_samples=n_samples, n_features=n_features, random_state=rng)

    # Create dataset with missing values
    X_missing = X.copy()
    X_missing[rng.choice([False, True], size=X.shape, p=[0.95, 0.05])] = np.nan
    assert np.isnan(X_missing).any()

    X_missing_train, X_missing_test, y_train, y_test = train_test_split(
        X_missing, y, random_state=0
    )

    # Train forest with missing values
    forest_with_missing = Forest(random_state=rng, n_estimators=50)
    forest_with_missing.fit(X_missing_train, y_train)
    score_with_missing = forest_with_missing.score(X_missing_test, y_test)

    # Train forest without missing values
    X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=0)
    forest = Forest(random_state=rng, n_estimators=50)
    forest.fit(X_train, y_train)
    score_without_missing = forest.score(X_test, y_test)

    # Score is still 80 percent of the forest's score that had no missing values
    assert score_with_missing >= 0.80 * score_without_missing


@pytest.mark.parametrize(
    "Forest",
    [
        RandomForestClassifier,
        RandomForestRegressor,
        ExtraTreesRegressor,
        ExtraTreesClassifier,
    ],
)
def test_missing_value_is_predictive(Forest):
    """Check that the forest learns when missing values are only present for
    a predictive feature."""
    rng = np.random.RandomState(0)
    n_samples = 300
    expected_score = 0.75

    X_non_predictive = rng.standard_normal(size=(n_samples, 10))
    y = rng.randint(0, high=2, size=n_samples)

    # Create a predictive feature using `y` and with some noise
    X_random_mask = rng.choice([False, True], size=n_samples, p=[0.95, 0.05])
    y_mask = y.astype(bool)
    y_mask[X_random_mask] = ~y_mask[X_random_mask]

    predictive_feature = rng.standard_normal(size=n_samples)
    predictive_feature[y_mask] = np.nan
    assert np.isnan(predictive_feature).any()

    X_predictive = X_non_predictive.copy()
    X_predictive[:, 5] = predictive_feature

    (
        X_predictive_train,
        X_predictive_test,
        X_non_predictive_train,
        X_non_predictive_test,
        y_train,
        y_test,
    ) = train_test_split(X_predictive, X_non_predictive, y, random_state=0)
    forest_predictive = Forest(random_state=0).fit(X_predictive_train, y_train)
    forest_non_predictive = Forest(random_state=0).fit(X_non_predictive_train, y_train)

    predictive_test_score = forest_predictive.score(X_predictive_test, y_test)

    assert predictive_test_score >= expected_score
    assert predictive_test_score >= forest_non_predictive.score(
        X_non_predictive_test, y_test
    )


@pytest.mark.parametrize("Forest", FOREST_REGRESSORS.values())
def test_non_supported_criterion_raises_error_with_missing_values(Forest):
    """Raise error for unsupported criterion when there are missing values."""
    X = np.array([[0, 1, 2], [np.nan, 0, 2.0]])
    y = [0.5, 1.0]

    forest = Forest(criterion="absolute_error")

    msg = ".*does not accept missing values"
    with pytest.raises(ValueError, match=msg):
        forest.fit(X, y)
