"""Test the search module"""

from collections import Iterable, Sized
from sklearn.externals.six.moves import cStringIO as StringIO
from sklearn.externals.six.moves import xrange
from sklearn.externals.joblib._compat import PY3_OR_LATER
from itertools import chain, product
import pickle
import sys
from types import GeneratorType
import re

import numpy as np
import scipy.sparse as sp

from sklearn.utils.fixes import sp_version
from sklearn.utils.testing import assert_equal
from sklearn.utils.testing import assert_not_equal
from sklearn.utils.testing import assert_raises
from sklearn.utils.testing import assert_warns
from sklearn.utils.testing import assert_warns_message
from sklearn.utils.testing import assert_raise_message
from sklearn.utils.testing import assert_false, assert_true
from sklearn.utils.testing import assert_array_equal
from sklearn.utils.testing import assert_array_almost_equal
from sklearn.utils.testing import assert_almost_equal
from sklearn.utils.testing import ignore_warnings
from sklearn.utils.mocking import CheckingClassifier, MockDataFrame

from scipy.stats import bernoulli, expon, uniform

from sklearn.base import BaseEstimator
from sklearn.base import clone
from sklearn.exceptions import NotFittedError
from sklearn.datasets import make_classification
from sklearn.datasets import make_blobs
from sklearn.datasets import make_multilabel_classification

from sklearn.model_selection import fit_grid_point
from sklearn.model_selection import KFold
from sklearn.model_selection import StratifiedKFold
from sklearn.model_selection import StratifiedShuffleSplit
from sklearn.model_selection import LeaveOneGroupOut
from sklearn.model_selection import LeavePGroupsOut
from sklearn.model_selection import GroupKFold
from sklearn.model_selection import GroupShuffleSplit
from sklearn.model_selection import GridSearchCV
from sklearn.model_selection import RandomizedSearchCV
from sklearn.model_selection import ParameterGrid
from sklearn.model_selection import ParameterSampler

from sklearn.model_selection._validation import FitFailedWarning

from sklearn.svm import LinearSVC, SVC
from sklearn.tree import DecisionTreeRegressor
from sklearn.tree import DecisionTreeClassifier
from sklearn.cluster import KMeans
from sklearn.neighbors import KernelDensity
from sklearn.metrics import f1_score
from sklearn.metrics import recall_score
from sklearn.metrics import accuracy_score
from sklearn.metrics import make_scorer
from sklearn.metrics import roc_auc_score
from sklearn.preprocessing import Imputer
from sklearn.pipeline import Pipeline
from sklearn.linear_model import Ridge, SGDClassifier

from sklearn.model_selection.tests.common import OneTimeSplitter


# Neither of the following two estimators inherit from BaseEstimator,
# to test hyperparameter search on user-defined classifiers.
class MockClassifier(object):
    """Dummy classifier to test the parameter search algorithms"""
    def __init__(self, foo_param=0):
        self.foo_param = foo_param

    def fit(self, X, Y):
        assert_true(len(X) == len(Y))
        self.classes_ = np.unique(Y)
        return self

    def predict(self, T):
        return T.shape[0]

    def transform(self, X):
        return X + self.foo_param

    def inverse_transform(self, X):
        return X - self.foo_param

    predict_proba = predict
    predict_log_proba = predict
    decision_function = predict

    def score(self, X=None, Y=None):
        if self.foo_param > 1:
            score = 1.
        else:
            score = 0.
        return score

    def get_params(self, deep=False):
        return {'foo_param': self.foo_param}

    def set_params(self, **params):
        self.foo_param = params['foo_param']
        return self


class LinearSVCNoScore(LinearSVC):
    """An LinearSVC classifier that has no score method."""
    @property
    def score(self):
        raise AttributeError

X = np.array([[-1, -1], [-2, -1], [1, 1], [2, 1]])
y = np.array([1, 1, 2, 2])


def assert_grid_iter_equals_getitem(grid):
    assert_equal(list(grid), [grid[i] for i in range(len(grid))])


def test_parameter_grid():
    # Test basic properties of ParameterGrid.
    params1 = {"foo": [1, 2, 3]}
    grid1 = ParameterGrid(params1)
    assert_true(isinstance(grid1, Iterable))
    assert_true(isinstance(grid1, Sized))
    assert_equal(len(grid1), 3)
    assert_grid_iter_equals_getitem(grid1)

    params2 = {"foo": [4, 2],
               "bar": ["ham", "spam", "eggs"]}
    grid2 = ParameterGrid(params2)
    assert_equal(len(grid2), 6)

    # loop to assert we can iterate over the grid multiple times
    for i in xrange(2):
        # tuple + chain transforms {"a": 1, "b": 2} to ("a", 1, "b", 2)
        points = set(tuple(chain(*(sorted(p.items())))) for p in grid2)
        assert_equal(points,
                     set(("bar", x, "foo", y)
                         for x, y in product(params2["bar"], params2["foo"])))
    assert_grid_iter_equals_getitem(grid2)

    # Special case: empty grid (useful to get default estimator settings)
    empty = ParameterGrid({})
    assert_equal(len(empty), 1)
    assert_equal(list(empty), [{}])
    assert_grid_iter_equals_getitem(empty)
    assert_raises(IndexError, lambda: empty[1])

    has_empty = ParameterGrid([{'C': [1, 10]}, {}, {'C': [.5]}])
    assert_equal(len(has_empty), 4)
    assert_equal(list(has_empty), [{'C': 1}, {'C': 10}, {}, {'C': .5}])
    assert_grid_iter_equals_getitem(has_empty)


def test_grid_search():
    # Test that the best estimator contains the right value for foo_param
    clf = MockClassifier()
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]}, verbose=3)
    # make sure it selects the smallest parameter in case of ties
    old_stdout = sys.stdout
    sys.stdout = StringIO()
    grid_search.fit(X, y)
    sys.stdout = old_stdout
    assert_equal(grid_search.best_estimator_.foo_param, 2)

    assert_array_equal(grid_search.cv_results_["param_foo_param"].data,
                       [1, 2, 3])

    # Smoke test the score etc:
    grid_search.score(X, y)
    grid_search.predict_proba(X)
    grid_search.decision_function(X)
    grid_search.transform(X)

    # Test exception handling on scoring
    grid_search.scoring = 'sklearn'
    assert_raises(ValueError, grid_search.fit, X, y)


def check_hyperparameter_searcher_with_fit_params(klass, **klass_kwargs):
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)
    clf = CheckingClassifier(expected_fit_params=['spam', 'eggs'])
    searcher = klass(clf, {'foo_param': [1, 2, 3]}, cv=2, **klass_kwargs)

    # The CheckingClassifer generates an assertion error if
    # a parameter is missing or has length != len(X).
    assert_raise_message(AssertionError,
                         "Expected fit parameter(s) ['eggs'] not seen.",
                         searcher.fit, X, y, spam=np.ones(10))
    assert_raise_message(AssertionError,
                         "Fit parameter spam has length 1; expected 4.",
                         searcher.fit, X, y, spam=np.ones(1),
                         eggs=np.zeros(10))
    searcher.fit(X, y, spam=np.ones(10), eggs=np.zeros(10))


def test_grid_search_with_fit_params():
    check_hyperparameter_searcher_with_fit_params(GridSearchCV)


def test_random_search_with_fit_params():
    check_hyperparameter_searcher_with_fit_params(RandomizedSearchCV, n_iter=1)


def test_grid_search_fit_params_deprecation():
    # NOTE: Remove this test in v0.21

    # Use of `fit_params` in the class constructor is deprecated,
    # but will still work until v0.21.
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)
    clf = CheckingClassifier(expected_fit_params=['spam'])
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]},
                               fit_params={'spam': np.ones(10)})
    assert_warns(DeprecationWarning, grid_search.fit, X, y)


def test_grid_search_fit_params_two_places():
    # NOTE: Remove this test in v0.21

    # If users try to input fit parameters in both
    # the constructor (deprecated use) and the `fit`
    # method, we'll ignore the values passed to the constructor.
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)
    clf = CheckingClassifier(expected_fit_params=['spam'])

    # The "spam" array is too short and will raise an
    # error in the CheckingClassifier if used.
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]},
                               fit_params={'spam': np.ones(1)})

    expected_warning = ('Ignoring fit_params passed as a constructor '
                        'argument in favor of keyword arguments to '
                        'the "fit" method.')
    assert_warns_message(RuntimeWarning, expected_warning,
                         grid_search.fit, X, y, spam=np.ones(10))

    # Verify that `fit` prefers its own kwargs by giving valid
    # kwargs in the constructor and invalid in the method call
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]},
                               fit_params={'spam': np.ones(10)})
    assert_raise_message(AssertionError, "Fit parameter spam has length 1",
                         grid_search.fit, X, y, spam=np.ones(1))


@ignore_warnings
def test_grid_search_no_score():
    # Test grid-search on classifier that has no score function.
    clf = LinearSVC(random_state=0)
    X, y = make_blobs(random_state=0, centers=2)
    Cs = [.1, 1, 10]
    clf_no_score = LinearSVCNoScore(random_state=0)
    grid_search = GridSearchCV(clf, {'C': Cs}, scoring='accuracy')
    grid_search.fit(X, y)

    grid_search_no_score = GridSearchCV(clf_no_score, {'C': Cs},
                                        scoring='accuracy')
    # smoketest grid search
    grid_search_no_score.fit(X, y)

    # check that best params are equal
    assert_equal(grid_search_no_score.best_params_, grid_search.best_params_)
    # check that we can call score and that it gives the correct result
    assert_equal(grid_search.score(X, y), grid_search_no_score.score(X, y))

    # giving no scoring function raises an error
    grid_search_no_score = GridSearchCV(clf_no_score, {'C': Cs})
    assert_raise_message(TypeError, "no scoring", grid_search_no_score.fit,
                         [[1]])


def test_grid_search_score_method():
    X, y = make_classification(n_samples=100, n_classes=2, flip_y=.2,
                               random_state=0)
    clf = LinearSVC(random_state=0)
    grid = {'C': [.1]}

    search_no_scoring = GridSearchCV(clf, grid, scoring=None).fit(X, y)
    search_accuracy = GridSearchCV(clf, grid, scoring='accuracy').fit(X, y)
    search_no_score_method_auc = GridSearchCV(LinearSVCNoScore(), grid,
                                              scoring='roc_auc').fit(X, y)
    search_auc = GridSearchCV(clf, grid, scoring='roc_auc').fit(X, y)

    # Check warning only occurs in situation where behavior changed:
    # estimator requires score method to compete with scoring parameter
    score_no_scoring = search_no_scoring.score(X, y)
    score_accuracy = search_accuracy.score(X, y)
    score_no_score_auc = search_no_score_method_auc.score(X, y)
    score_auc = search_auc.score(X, y)

    # ensure the test is sane
    assert_true(score_auc < 1.0)
    assert_true(score_accuracy < 1.0)
    assert_not_equal(score_auc, score_accuracy)

    assert_almost_equal(score_accuracy, score_no_scoring)
    assert_almost_equal(score_auc, score_no_score_auc)


def test_grid_search_groups():
    # Check if ValueError (when groups is None) propagates to GridSearchCV
    # And also check if groups is correctly passed to the cv object
    rng = np.random.RandomState(0)

    X, y = make_classification(n_samples=15, n_classes=2, random_state=0)
    groups = rng.randint(0, 3, 15)

    clf = LinearSVC(random_state=0)
    grid = {'C': [1]}

    group_cvs = [LeaveOneGroupOut(), LeavePGroupsOut(2), GroupKFold(),
                 GroupShuffleSplit()]
    for cv in group_cvs:
        gs = GridSearchCV(clf, grid, cv=cv)
        assert_raise_message(ValueError,
                             "The 'groups' parameter should not be None.",
                             gs.fit, X, y)
        gs.fit(X, y, groups=groups)

    non_group_cvs = [StratifiedKFold(), StratifiedShuffleSplit()]
    for cv in non_group_cvs:
        gs = GridSearchCV(clf, grid, cv=cv)
        # Should not raise an error
        gs.fit(X, y)


def test_classes__property():
    # Test that classes_ property matches best_estimator_.classes_
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)
    Cs = [.1, 1, 10]

    grid_search = GridSearchCV(LinearSVC(random_state=0), {'C': Cs})
    grid_search.fit(X, y)
    assert_array_equal(grid_search.best_estimator_.classes_,
                       grid_search.classes_)

    # Test that regressors do not have a classes_ attribute
    grid_search = GridSearchCV(Ridge(), {'alpha': [1.0, 2.0]})
    grid_search.fit(X, y)
    assert_false(hasattr(grid_search, 'classes_'))

    # Test that the grid searcher has no classes_ attribute before it's fit
    grid_search = GridSearchCV(LinearSVC(random_state=0), {'C': Cs})
    assert_false(hasattr(grid_search, 'classes_'))

    # Test that the grid searcher has no classes_ attribute without a refit
    grid_search = GridSearchCV(LinearSVC(random_state=0),
                               {'C': Cs}, refit=False)
    grid_search.fit(X, y)
    assert_false(hasattr(grid_search, 'classes_'))


def test_trivial_cv_results_attr():
    # Test search over a "grid" with only one point.
    # Non-regression test: grid_scores_ wouldn't be set by GridSearchCV.
    clf = MockClassifier()
    grid_search = GridSearchCV(clf, {'foo_param': [1]})
    grid_search.fit(X, y)
    assert_true(hasattr(grid_search, "cv_results_"))

    random_search = RandomizedSearchCV(clf, {'foo_param': [0]}, n_iter=1)
    random_search.fit(X, y)
    assert_true(hasattr(grid_search, "cv_results_"))


def test_no_refit():
    # Test that GSCV can be used for model selection alone without refitting
    clf = MockClassifier()
    for scoring in [None, ['accuracy', 'precision']]:
        grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]}, refit=False)
        grid_search.fit(X, y)
        assert_true(not hasattr(grid_search, "best_estimator_") and
                    hasattr(grid_search, "best_index_") and
                    hasattr(grid_search, "best_params_"))

        # Make sure the functions predict/transform etc raise meaningful
        # error messages
        for fn_name in ('predict', 'predict_proba', 'predict_log_proba',
                        'transform', 'inverse_transform'):
            assert_raise_message(NotFittedError,
                                 ('refit=False. %s is available only after '
                                  'refitting on the best parameters'
                                  % fn_name), getattr(grid_search, fn_name), X)

    # Test that an invalid refit param raises appropriate error messages
    for refit in ["", 5, True, 'recall', 'accuracy']:
        assert_raise_message(ValueError, "For multi-metric scoring, the "
                             "parameter refit must be set to a scorer key",
                             GridSearchCV(clf, {}, refit=refit,
                                          scoring={'acc': 'accuracy',
                                                   'prec': 'precision'}).fit,
                             X, y)


def test_grid_search_error():
    # Test that grid search will capture errors on data with different length
    X_, y_ = make_classification(n_samples=200, n_features=100, random_state=0)

    clf = LinearSVC()
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]})
    assert_raises(ValueError, cv.fit, X_[:180], y_)


def test_grid_search_one_grid_point():
    X_, y_ = make_classification(n_samples=200, n_features=100, random_state=0)
    param_dict = {"C": [1.0], "kernel": ["rbf"], "gamma": [0.1]}

    clf = SVC()
    cv = GridSearchCV(clf, param_dict)
    cv.fit(X_, y_)

    clf = SVC(C=1.0, kernel="rbf", gamma=0.1)
    clf.fit(X_, y_)

    assert_array_equal(clf.dual_coef_, cv.best_estimator_.dual_coef_)


def test_grid_search_when_param_grid_includes_range():
    # Test that the best estimator contains the right value for foo_param
    clf = MockClassifier()
    grid_search = None
    if PY3_OR_LATER:
        grid_search = GridSearchCV(clf, {'foo_param': range(1, 4)})
    else:
        grid_search = GridSearchCV(clf, {'foo_param': xrange(1, 4)})
    grid_search.fit(X, y)
    assert_equal(grid_search.best_estimator_.foo_param, 2)


def test_grid_search_bad_param_grid():
    param_dict = {"C": 1.0}
    clf = SVC()
    assert_raise_message(
        ValueError,
        "Parameter values for parameter (C) need to be a sequence"
        "(but not a string) or np.ndarray.",
        GridSearchCV, clf, param_dict)

    param_dict = {"C": []}
    clf = SVC()
    assert_raise_message(
        ValueError,
        "Parameter values for parameter (C) need to be a non-empty sequence.",
        GridSearchCV, clf, param_dict)

    param_dict = {"C": "1,2,3"}
    clf = SVC()
    assert_raise_message(
        ValueError,
        "Parameter values for parameter (C) need to be a sequence"
        "(but not a string) or np.ndarray.",
        GridSearchCV, clf, param_dict)

    param_dict = {"C": np.ones(6).reshape(3, 2)}
    clf = SVC()
    assert_raises(ValueError, GridSearchCV, clf, param_dict)


def test_grid_search_sparse():
    # Test that grid search works with both dense and sparse matrices
    X_, y_ = make_classification(n_samples=200, n_features=100, random_state=0)

    clf = LinearSVC()
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]})
    cv.fit(X_[:180], y_[:180])
    y_pred = cv.predict(X_[180:])
    C = cv.best_estimator_.C

    X_ = sp.csr_matrix(X_)
    clf = LinearSVC()
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]})
    cv.fit(X_[:180].tocoo(), y_[:180])
    y_pred2 = cv.predict(X_[180:])
    C2 = cv.best_estimator_.C

    assert_true(np.mean(y_pred == y_pred2) >= .9)
    assert_equal(C, C2)


def test_grid_search_sparse_scoring():
    X_, y_ = make_classification(n_samples=200, n_features=100, random_state=0)

    clf = LinearSVC()
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]}, scoring="f1")
    cv.fit(X_[:180], y_[:180])
    y_pred = cv.predict(X_[180:])
    C = cv.best_estimator_.C

    X_ = sp.csr_matrix(X_)
    clf = LinearSVC()
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]}, scoring="f1")
    cv.fit(X_[:180], y_[:180])
    y_pred2 = cv.predict(X_[180:])
    C2 = cv.best_estimator_.C

    assert_array_equal(y_pred, y_pred2)
    assert_equal(C, C2)
    # Smoke test the score
    # np.testing.assert_allclose(f1_score(cv.predict(X_[:180]), y[:180]),
    #                            cv.score(X_[:180], y[:180]))

    # test loss where greater is worse
    def f1_loss(y_true_, y_pred_):
        return -f1_score(y_true_, y_pred_)
    F1Loss = make_scorer(f1_loss, greater_is_better=False)
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]}, scoring=F1Loss)
    cv.fit(X_[:180], y_[:180])
    y_pred3 = cv.predict(X_[180:])
    C3 = cv.best_estimator_.C

    assert_equal(C, C3)
    assert_array_equal(y_pred, y_pred3)


def test_grid_search_precomputed_kernel():
    # Test that grid search works when the input features are given in the
    # form of a precomputed kernel matrix
    X_, y_ = make_classification(n_samples=200, n_features=100, random_state=0)

    # compute the training kernel matrix corresponding to the linear kernel
    K_train = np.dot(X_[:180], X_[:180].T)
    y_train = y_[:180]

    clf = SVC(kernel='precomputed')
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]})
    cv.fit(K_train, y_train)

    assert_true(cv.best_score_ >= 0)

    # compute the test kernel matrix
    K_test = np.dot(X_[180:], X_[:180].T)
    y_test = y_[180:]

    y_pred = cv.predict(K_test)

    assert_true(np.mean(y_pred == y_test) >= 0)

    # test error is raised when the precomputed kernel is not array-like
    # or sparse
    assert_raises(ValueError, cv.fit, K_train.tolist(), y_train)


def test_grid_search_precomputed_kernel_error_nonsquare():
    # Test that grid search returns an error with a non-square precomputed
    # training kernel matrix
    K_train = np.zeros((10, 20))
    y_train = np.ones((10, ))
    clf = SVC(kernel='precomputed')
    cv = GridSearchCV(clf, {'C': [0.1, 1.0]})
    assert_raises(ValueError, cv.fit, K_train, y_train)


class BrokenClassifier(BaseEstimator):
    """Broken classifier that cannot be fit twice"""

    def __init__(self, parameter=None):
        self.parameter = parameter

    def fit(self, X, y):
        assert_true(not hasattr(self, 'has_been_fit_'))
        self.has_been_fit_ = True

    def predict(self, X):
        return np.zeros(X.shape[0])


@ignore_warnings
def test_refit():
    # Regression test for bug in refitting
    # Simulates re-fitting a broken estimator; this used to break with
    # sparse SVMs.
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)

    clf = GridSearchCV(BrokenClassifier(), [{'parameter': [0, 1]}],
                       scoring="precision", refit=True)
    clf.fit(X, y)


def test_gridsearch_nd():
    # Pass X as list in GridSearchCV
    X_4d = np.arange(10 * 5 * 3 * 2).reshape(10, 5, 3, 2)
    y_3d = np.arange(10 * 7 * 11).reshape(10, 7, 11)
    check_X = lambda x: x.shape[1:] == (5, 3, 2)
    check_y = lambda x: x.shape[1:] == (7, 11)
    clf = CheckingClassifier(check_X=check_X, check_y=check_y)
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]})
    grid_search.fit(X_4d, y_3d).score(X, y)
    assert_true(hasattr(grid_search, "cv_results_"))


def test_X_as_list():
    # Pass X as list in GridSearchCV
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)

    clf = CheckingClassifier(check_X=lambda x: isinstance(x, list))
    cv = KFold(n_splits=3)
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]}, cv=cv)
    grid_search.fit(X.tolist(), y).score(X, y)
    assert_true(hasattr(grid_search, "cv_results_"))


def test_y_as_list():
    # Pass y as list in GridSearchCV
    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)

    clf = CheckingClassifier(check_y=lambda x: isinstance(x, list))
    cv = KFold(n_splits=3)
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]}, cv=cv)
    grid_search.fit(X, y.tolist()).score(X, y)
    assert_true(hasattr(grid_search, "cv_results_"))


@ignore_warnings
def test_pandas_input():
    # check cross_val_score doesn't destroy pandas dataframe
    types = [(MockDataFrame, MockDataFrame)]
    try:
        from pandas import Series, DataFrame
        types.append((DataFrame, Series))
    except ImportError:
        pass

    X = np.arange(100).reshape(10, 10)
    y = np.array([0] * 5 + [1] * 5)

    for InputFeatureType, TargetType in types:
        # X dataframe, y series
        X_df, y_ser = InputFeatureType(X), TargetType(y)

        def check_df(x):
            return isinstance(x, InputFeatureType)

        def check_series(x):
            return isinstance(x, TargetType)

        clf = CheckingClassifier(check_X=check_df, check_y=check_series)

        grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]})
        grid_search.fit(X_df, y_ser).score(X_df, y_ser)
        grid_search.predict(X_df)
        assert_true(hasattr(grid_search, "cv_results_"))


def test_unsupervised_grid_search():
    # test grid-search with unsupervised estimator
    X, y = make_blobs(random_state=0)
    km = KMeans(random_state=0)

    # Multi-metric evaluation unsupervised
    scoring = ['adjusted_rand_score', 'fowlkes_mallows_score']
    for refit in ['adjusted_rand_score', 'fowlkes_mallows_score']:
        grid_search = GridSearchCV(km, param_grid=dict(n_clusters=[2, 3, 4]),
                                   scoring=scoring, refit=refit)
        grid_search.fit(X, y)
        # Both ARI and FMS can find the right number :)
        assert_equal(grid_search.best_params_["n_clusters"], 3)

    # Single metric evaluation unsupervised
    grid_search = GridSearchCV(km, param_grid=dict(n_clusters=[2, 3, 4]),
                               scoring='fowlkes_mallows_score')
    grid_search.fit(X, y)
    assert_equal(grid_search.best_params_["n_clusters"], 3)

    # Now without a score, and without y
    grid_search = GridSearchCV(km, param_grid=dict(n_clusters=[2, 3, 4]))
    grid_search.fit(X)
    assert_equal(grid_search.best_params_["n_clusters"], 4)


def test_gridsearch_no_predict():
    # test grid-search with an estimator without predict.
    # slight duplication of a test from KDE
    def custom_scoring(estimator, X):
        return 42 if estimator.bandwidth == .1 else 0
    X, _ = make_blobs(cluster_std=.1, random_state=1,
                      centers=[[0, 1], [1, 0], [0, 0]])
    search = GridSearchCV(KernelDensity(),
                          param_grid=dict(bandwidth=[.01, .1, 1]),
                          scoring=custom_scoring)
    search.fit(X)
    assert_equal(search.best_params_['bandwidth'], .1)
    assert_equal(search.best_score_, 42)


def test_param_sampler():
    # test basic properties of param sampler
    param_distributions = {"kernel": ["rbf", "linear"],
                           "C": uniform(0, 1)}
    sampler = ParameterSampler(param_distributions=param_distributions,
                               n_iter=10, random_state=0)
    samples = [x for x in sampler]
    assert_equal(len(samples), 10)
    for sample in samples:
        assert_true(sample["kernel"] in ["rbf", "linear"])
        assert_true(0 <= sample["C"] <= 1)

    # test that repeated calls yield identical parameters
    param_distributions = {"C": [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]}
    sampler = ParameterSampler(param_distributions=param_distributions,
                               n_iter=3, random_state=0)
    assert_equal([x for x in sampler], [x for x in sampler])

    if sp_version >= (0, 16):
        param_distributions = {"C": uniform(0, 1)}
        sampler = ParameterSampler(param_distributions=param_distributions,
                                   n_iter=10, random_state=0)
        assert_equal([x for x in sampler], [x for x in sampler])


def check_cv_results_array_types(search, param_keys, score_keys):
    # Check if the search `cv_results`'s array are of correct types
    cv_results = search.cv_results_
    assert_true(all(isinstance(cv_results[param], np.ma.MaskedArray)
                    for param in param_keys))
    assert_true(all(cv_results[key].dtype == object for key in param_keys))
    assert_false(any(isinstance(cv_results[key], np.ma.MaskedArray)
                     for key in score_keys))
    assert_true(all(cv_results[key].dtype == np.float64
                    for key in score_keys if not key.startswith('rank')))

    scorer_keys = search.scorer_.keys() if search.multimetric_ else ['score']

    for key in scorer_keys:
        assert_true(cv_results['rank_test_%s' % key].dtype == np.int32)


def check_cv_results_keys(cv_results, param_keys, score_keys, n_cand):
    # Test the search.cv_results_ contains all the required results
    assert_array_equal(sorted(cv_results.keys()),
                       sorted(param_keys + score_keys + ('params',)))
    assert_true(all(cv_results[key].shape == (n_cand,)
                    for key in param_keys + score_keys))


def check_cv_results_grid_scores_consistency(search):
    # TODO Remove test in 0.20
    if search.multimetric_:
        assert_raise_message(AttributeError, "not available for multi-metric",
                             getattr, search, 'grid_scores_')
    else:
        cv_results = search.cv_results_
        res_scores = np.vstack(list([cv_results["split%d_test_score" % i]
                                     for i in range(search.n_splits_)])).T
        res_means = cv_results["mean_test_score"]
        res_params = cv_results["params"]
        n_cand = len(res_params)
        grid_scores = assert_warns(DeprecationWarning, getattr,
                                   search, 'grid_scores_')
        assert_equal(len(grid_scores), n_cand)
        # Check consistency of the structure of grid_scores
        for i in range(n_cand):
            assert_equal(grid_scores[i].parameters, res_params[i])
            assert_array_equal(grid_scores[i].cv_validation_scores,
                               res_scores[i, :])
            assert_array_equal(grid_scores[i].mean_validation_score,
                               res_means[i])


def test_grid_search_cv_results():
    X, y = make_classification(n_samples=50, n_features=4,
                               random_state=42)

    n_splits = 3
    n_grid_points = 6
    params = [dict(kernel=['rbf', ], C=[1, 10], gamma=[0.1, 1]),
              dict(kernel=['poly', ], degree=[1, 2])]

    param_keys = ('param_C', 'param_degree', 'param_gamma', 'param_kernel')
    score_keys = ('mean_test_score', 'mean_train_score',
                  'rank_test_score',
                  'split0_test_score', 'split1_test_score',
                  'split2_test_score',
                  'split0_train_score', 'split1_train_score',
                  'split2_train_score',
                  'std_test_score', 'std_train_score',
                  'mean_fit_time', 'std_fit_time',
                  'mean_score_time', 'std_score_time')
    n_candidates = n_grid_points

    for iid in (False, True):
        search = GridSearchCV(SVC(), cv=n_splits, iid=iid, param_grid=params)
        search.fit(X, y)
        assert_equal(iid, search.iid)
        cv_results = search.cv_results_
        # Check if score and timing are reasonable
        assert_true(all(cv_results['rank_test_score'] >= 1))
        assert_true(all(cv_results[k] >= 0) for k in score_keys
                    if k is not 'rank_test_score')
        assert_true(all(cv_results[k] <= 1) for k in score_keys
                    if 'time' not in k and
                    k is not 'rank_test_score')
        # Check cv_results structure
        check_cv_results_array_types(search, param_keys, score_keys)
        check_cv_results_keys(cv_results, param_keys, score_keys, n_candidates)
        # Check masking
        cv_results = search.cv_results_
        n_candidates = len(search.cv_results_['params'])
        assert_true(all((cv_results['param_C'].mask[i] and
                         cv_results['param_gamma'].mask[i] and
                         not cv_results['param_degree'].mask[i])
                        for i in range(n_candidates)
                        if cv_results['param_kernel'][i] == 'linear'))
        assert_true(all((not cv_results['param_C'].mask[i] and
                         not cv_results['param_gamma'].mask[i] and
                         cv_results['param_degree'].mask[i])
                        for i in range(n_candidates)
                        if cv_results['param_kernel'][i] == 'rbf'))
        check_cv_results_grid_scores_consistency(search)


def test_random_search_cv_results():
    X, y = make_classification(n_samples=50, n_features=4, random_state=42)

    n_splits = 3
    n_search_iter = 30

    params = dict(C=expon(scale=10), gamma=expon(scale=0.1))
    param_keys = ('param_C', 'param_gamma')
    score_keys = ('mean_test_score', 'mean_train_score',
                  'rank_test_score',
                  'split0_test_score', 'split1_test_score',
                  'split2_test_score',
                  'split0_train_score', 'split1_train_score',
                  'split2_train_score',
                  'std_test_score', 'std_train_score',
                  'mean_fit_time', 'std_fit_time',
                  'mean_score_time', 'std_score_time')
    n_cand = n_search_iter

    for iid in (False, True):
        search = RandomizedSearchCV(SVC(), n_iter=n_search_iter, cv=n_splits,
                                    iid=iid, param_distributions=params)
        search.fit(X, y)
        assert_equal(iid, search.iid)
        cv_results = search.cv_results_
        # Check results structure
        check_cv_results_array_types(search, param_keys, score_keys)
        check_cv_results_keys(cv_results, param_keys, score_keys, n_cand)
        # For random_search, all the param array vals should be unmasked
        assert_false(any(cv_results['param_C'].mask) or
                     any(cv_results['param_gamma'].mask))
        check_cv_results_grid_scores_consistency(search)


def test_search_iid_param():
    # Test the IID parameter
    # noise-free simple 2d-data
    X, y = make_blobs(centers=[[0, 0], [1, 0], [0, 1], [1, 1]], random_state=0,
                      cluster_std=0.1, shuffle=False, n_samples=80)
    # split dataset into two folds that are not iid
    # first one contains data of all 4 blobs, second only from two.
    mask = np.ones(X.shape[0], dtype=np.bool)
    mask[np.where(y == 1)[0][::2]] = 0
    mask[np.where(y == 2)[0][::2]] = 0
    # this leads to perfect classification on one fold and a score of 1/3 on
    # the other
    # create "cv" for splits
    cv = [[mask, ~mask], [~mask, mask]]
    # once with iid=True (default)
    grid_search = GridSearchCV(SVC(), param_grid={'C': [1, 10]}, cv=cv)
    random_search = RandomizedSearchCV(SVC(), n_iter=2,
                                       param_distributions={'C': [1, 10]},
                                       cv=cv)
    for search in (grid_search, random_search):
        search.fit(X, y)
        assert_true(search.iid)

        test_cv_scores = np.array(list(search.cv_results_['split%d_test_score'
                                                          % s_i][0]
                                       for s_i in range(search.n_splits_)))
        train_cv_scores = np.array(list(search.cv_results_['split%d_train_'
                                                           'score' % s_i][0]
                                        for s_i in range(search.n_splits_)))
        test_mean = search.cv_results_['mean_test_score'][0]
        test_std = search.cv_results_['std_test_score'][0]

        train_cv_scores = np.array(list(search.cv_results_['split%d_train_'
                                                           'score' % s_i][0]
                                        for s_i in range(search.n_splits_)))
        train_mean = search.cv_results_['mean_train_score'][0]
        train_std = search.cv_results_['std_train_score'][0]

        # Test the first candidate
        assert_equal(search.cv_results_['param_C'][0], 1)
        assert_array_almost_equal(test_cv_scores, [1, 1. / 3.])
        assert_array_almost_equal(train_cv_scores, [1, 1])

        # for first split, 1/4 of dataset is in test, for second 3/4.
        # take weighted average and weighted std
        expected_test_mean = 1 * 1. / 4. + 1. / 3. * 3. / 4.
        expected_test_std = np.sqrt(1. / 4 * (expected_test_mean - 1) ** 2 +
                                    3. / 4 * (expected_test_mean - 1. / 3.) **
                                    2)
        assert_almost_equal(test_mean, expected_test_mean)
        assert_almost_equal(test_std, expected_test_std)

        # For the train scores, we do not take a weighted mean irrespective of
        # i.i.d. or not
        assert_almost_equal(train_mean, 1)
        assert_almost_equal(train_std, 0)

    # once with iid=False
    grid_search = GridSearchCV(SVC(),
                               param_grid={'C': [1, 10]},
                               cv=cv, iid=False)
    random_search = RandomizedSearchCV(SVC(), n_iter=2,
                                       param_distributions={'C': [1, 10]},
                                       cv=cv, iid=False)

    for search in (grid_search, random_search):
        search.fit(X, y)
        assert_false(search.iid)

        test_cv_scores = np.array(list(search.cv_results_['split%d_test_score'
                                                          % s][0]
                                       for s in range(search.n_splits_)))
        test_mean = search.cv_results_['mean_test_score'][0]
        test_std = search.cv_results_['std_test_score'][0]

        train_cv_scores = np.array(list(search.cv_results_['split%d_train_'
                                                           'score' % s][0]
                                        for s in range(search.n_splits_)))
        train_mean = search.cv_results_['mean_train_score'][0]
        train_std = search.cv_results_['std_train_score'][0]

        assert_equal(search.cv_results_['param_C'][0], 1)
        # scores are the same as above
        assert_array_almost_equal(test_cv_scores, [1, 1. / 3.])
        # Unweighted mean/std is used
        assert_almost_equal(test_mean, np.mean(test_cv_scores))
        assert_almost_equal(test_std, np.std(test_cv_scores))

        # For the train scores, we do not take a weighted mean irrespective of
        # i.i.d. or not
        assert_almost_equal(train_mean, 1)
        assert_almost_equal(train_std, 0)


def test_grid_search_cv_results_multimetric():
    X, y = make_classification(n_samples=50, n_features=4, random_state=42)

    n_splits = 3
    params = [dict(kernel=['rbf', ], C=[1, 10], gamma=[0.1, 1]),
              dict(kernel=['poly', ], degree=[1, 2])]

    for iid in (False, True):
        grid_searches = []
        for scoring in ({'accuracy': make_scorer(accuracy_score),
                         'recall': make_scorer(recall_score)},
                        'accuracy', 'recall'):
            grid_search = GridSearchCV(SVC(), cv=n_splits, iid=iid,
                                       param_grid=params, scoring=scoring,
                                       refit=False)
            grid_search.fit(X, y)
            assert_equal(grid_search.iid, iid)
            grid_searches.append(grid_search)

        compare_cv_results_multimetric_with_single(*grid_searches, iid=iid)


def test_random_search_cv_results_multimetric():
    X, y = make_classification(n_samples=50, n_features=4, random_state=42)

    n_splits = 3
    n_search_iter = 30
    scoring = ('accuracy', 'recall')

    # Scipy 0.12's stats dists do not accept seed, hence we use param grid
    params = dict(C=np.logspace(-10, 1), gamma=np.logspace(-5, 0, base=0.1))
    for iid in (True, False):
        for refit in (True, False):
            random_searches = []
            for scoring in (('accuracy', 'recall'), 'accuracy', 'recall'):
                # If True, for multi-metric pass refit='accuracy'
                if refit:
                    refit = 'accuracy' if isinstance(scoring, tuple) else refit
                clf = SVC(probability=True, random_state=42)
                random_search = RandomizedSearchCV(clf, n_iter=n_search_iter,
                                                   cv=n_splits, iid=iid,
                                                   param_distributions=params,
                                                   scoring=scoring,
                                                   refit=refit, random_state=0)
                random_search.fit(X, y)
                random_searches.append(random_search)

            compare_cv_results_multimetric_with_single(*random_searches,
                                                       iid=iid)
            if refit:
                compare_refit_methods_when_refit_with_acc(
                    random_searches[0], random_searches[1], refit)


def compare_cv_results_multimetric_with_single(
        search_multi, search_acc, search_rec, iid):
    """Compare multi-metric cv_results with the ensemble of multiple
    single metric cv_results from single metric grid/random search"""

    assert_equal(search_multi.iid, iid)
    assert_true(search_multi.multimetric_)
    assert_array_equal(sorted(search_multi.scorer_),
                       ('accuracy', 'recall'))

    cv_results_multi = search_multi.cv_results_
    cv_results_acc_rec = {re.sub('_score$', '_accuracy', k): v
                          for k, v in search_acc.cv_results_.items()}
    cv_results_acc_rec.update({re.sub('_score$', '_recall', k): v
                               for k, v in search_rec.cv_results_.items()})

    # Check if score and timing are reasonable, also checks if the keys
    # are present
    assert_true(all((np.all(cv_results_multi[k] <= 1) for k in (
                    'mean_score_time', 'std_score_time', 'mean_fit_time',
                    'std_fit_time'))))

    # Compare the keys, other than time keys, among multi-metric and
    # single metric grid search results. np.testing.assert_equal performs a
    # deep nested comparison of the two cv_results dicts
    np.testing.assert_equal({k: v for k, v in cv_results_multi.items()
                             if not k.endswith('_time')},
                            {k: v for k, v in cv_results_acc_rec.items()
                             if not k.endswith('_time')})


def compare_refit_methods_when_refit_with_acc(search_multi, search_acc, refit):
    """Compare refit multi-metric search methods with single metric methods"""
    if refit:
        assert_equal(search_multi.refit, 'accuracy')
    else:
        assert_false(search_multi.refit)
    assert_equal(search_acc.refit, refit)

    X, y = make_blobs(n_samples=100, n_features=4, random_state=42)
    for method in ('predict', 'predict_proba', 'predict_log_proba'):
        assert_almost_equal(getattr(search_multi, method)(X),
                            getattr(search_acc, method)(X))
    assert_almost_equal(search_multi.score(X, y), search_acc.score(X, y))
    for key in ('best_index_', 'best_score_', 'best_params_'):
        assert_equal(getattr(search_multi, key), getattr(search_acc, key))


def test_search_cv_results_rank_tie_breaking():
    X, y = make_blobs(n_samples=50, random_state=42)

    # The two C values are close enough to give similar models
    # which would result in a tie of their mean cv-scores
    param_grid = {'C': [1, 1.001, 0.001]}

    grid_search = GridSearchCV(SVC(), param_grid=param_grid)
    random_search = RandomizedSearchCV(SVC(), n_iter=3,
                                       param_distributions=param_grid)

    for search in (grid_search, random_search):
        search.fit(X, y)
        cv_results = search.cv_results_
        # Check tie breaking strategy -
        # Check that there is a tie in the mean scores between
        # candidates 1 and 2 alone
        assert_almost_equal(cv_results['mean_test_score'][0],
                            cv_results['mean_test_score'][1])
        assert_almost_equal(cv_results['mean_train_score'][0],
                            cv_results['mean_train_score'][1])
        assert_false(np.allclose(cv_results['mean_test_score'][1],
                                 cv_results['mean_test_score'][2]))
        assert_false(np.allclose(cv_results['mean_train_score'][1],
                                 cv_results['mean_train_score'][2]))
        # 'min' rank should be assigned to the tied candidates
        assert_almost_equal(search.cv_results_['rank_test_score'], [1, 1, 3])


def test_search_cv_results_none_param():
    X, y = [[1], [2], [3], [4], [5]], [0, 0, 0, 0, 1]
    estimators = (DecisionTreeRegressor(), DecisionTreeClassifier())
    est_parameters = {"random_state": [0, None]}
    cv = KFold(random_state=0)

    for est in estimators:
        grid_search = GridSearchCV(est, est_parameters, cv=cv).fit(X, y)
        assert_array_equal(grid_search.cv_results_['param_random_state'],
                           [0, None])


@ignore_warnings()
def test_search_cv_timing():
    svc = LinearSVC(random_state=0)

    X = [[1, ], [2, ], [3, ], [4, ]]
    y = [0, 1, 1, 0]

    gs = GridSearchCV(svc, {'C': [0, 1]}, cv=2, error_score=0)
    rs = RandomizedSearchCV(svc, {'C': [0, 1]}, cv=2, error_score=0, n_iter=2)

    for search in (gs, rs):
        search.fit(X, y)
        for key in ['mean_fit_time', 'std_fit_time']:
            # NOTE The precision of time.time in windows is not high
            # enough for the fit/score times to be non-zero for trivial X and y
            assert_true(np.all(search.cv_results_[key] >= 0))
            assert_true(np.all(search.cv_results_[key] < 1))

        for key in ['mean_score_time', 'std_score_time']:
            assert_true(search.cv_results_[key][1] >= 0)
            assert_true(search.cv_results_[key][0] == 0.0)
            assert_true(np.all(search.cv_results_[key] < 1))


def test_grid_search_correct_score_results():
    # test that correct scores are used
    n_splits = 3
    clf = LinearSVC(random_state=0)
    X, y = make_blobs(random_state=0, centers=2)
    Cs = [.1, 1, 10]
    for score in ['f1', 'roc_auc']:
        grid_search = GridSearchCV(clf, {'C': Cs}, scoring=score, cv=n_splits)
        cv_results = grid_search.fit(X, y).cv_results_

        # Test scorer names
        result_keys = list(cv_results.keys())
        expected_keys = (("mean_test_score", "rank_test_score") +
                         tuple("split%d_test_score" % cv_i
                               for cv_i in range(n_splits)))
        assert_true(all(np.in1d(expected_keys, result_keys)))

        cv = StratifiedKFold(n_splits=n_splits)
        n_splits = grid_search.n_splits_
        for candidate_i, C in enumerate(Cs):
            clf.set_params(C=C)
            cv_scores = np.array(
                list(grid_search.cv_results_['split%d_test_score'
                                             % s][candidate_i]
                     for s in range(n_splits)))
            for i, (train, test) in enumerate(cv.split(X, y)):
                clf.fit(X[train], y[train])
                if score == "f1":
                    correct_score = f1_score(y[test], clf.predict(X[test]))
                elif score == "roc_auc":
                    dec = clf.decision_function(X[test])
                    correct_score = roc_auc_score(y[test], dec)
                assert_almost_equal(correct_score, cv_scores[i])


def test_fit_grid_point():
    X, y = make_classification(random_state=0)
    cv = StratifiedKFold(random_state=0)
    svc = LinearSVC(random_state=0)
    scorer = make_scorer(accuracy_score)

    for params in ({'C': 0.1}, {'C': 0.01}, {'C': 0.001}):
        for train, test in cv.split(X, y):
            this_scores, this_params, n_test_samples = fit_grid_point(
                X, y, clone(svc), params, train, test,
                scorer, verbose=False)

            est = clone(svc).set_params(**params)
            est.fit(X[train], y[train])
            expected_score = scorer(est, X[test], y[test])

            # Test the return values of fit_grid_point
            assert_almost_equal(this_scores, expected_score)
            assert_equal(params, this_params)
            assert_equal(n_test_samples, test.size)

    # Should raise an error upon multimetric scorer
    assert_raise_message(ValueError, "scoring value should either be a "
                         "callable, string or None.", fit_grid_point, X, y,
                         svc, params, train, test, {'score': scorer},
                         verbose=True)


def test_pickle():
    # Test that a fit search can be pickled
    clf = MockClassifier()
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]}, refit=True)
    grid_search.fit(X, y)
    grid_search_pickled = pickle.loads(pickle.dumps(grid_search))
    assert_array_almost_equal(grid_search.predict(X),
                              grid_search_pickled.predict(X))

    random_search = RandomizedSearchCV(clf, {'foo_param': [1, 2, 3]},
                                       refit=True, n_iter=3)
    random_search.fit(X, y)
    random_search_pickled = pickle.loads(pickle.dumps(random_search))
    assert_array_almost_equal(random_search.predict(X),
                              random_search_pickled.predict(X))


def test_grid_search_with_multioutput_data():
    # Test search with multi-output estimator

    X, y = make_multilabel_classification(return_indicator=True,
                                          random_state=0)

    est_parameters = {"max_depth": [1, 2, 3, 4]}
    cv = KFold(random_state=0)

    estimators = [DecisionTreeRegressor(random_state=0),
                  DecisionTreeClassifier(random_state=0)]

    # Test with grid search cv
    for est in estimators:
        grid_search = GridSearchCV(est, est_parameters, cv=cv)
        grid_search.fit(X, y)
        res_params = grid_search.cv_results_['params']
        for cand_i in range(len(res_params)):
            est.set_params(**res_params[cand_i])

            for i, (train, test) in enumerate(cv.split(X, y)):
                est.fit(X[train], y[train])
                correct_score = est.score(X[test], y[test])
                assert_almost_equal(
                    correct_score,
                    grid_search.cv_results_['split%d_test_score' % i][cand_i])

    # Test with a randomized search
    for est in estimators:
        random_search = RandomizedSearchCV(est, est_parameters,
                                           cv=cv, n_iter=3)
        random_search.fit(X, y)
        res_params = random_search.cv_results_['params']
        for cand_i in range(len(res_params)):
            est.set_params(**res_params[cand_i])

            for i, (train, test) in enumerate(cv.split(X, y)):
                est.fit(X[train], y[train])
                correct_score = est.score(X[test], y[test])
                assert_almost_equal(
                    correct_score,
                    random_search.cv_results_['split%d_test_score'
                                              % i][cand_i])


def test_predict_proba_disabled():
    # Test predict_proba when disabled on estimator.
    X = np.arange(20).reshape(5, -1)
    y = [0, 0, 1, 1, 1]
    clf = SVC(probability=False)
    gs = GridSearchCV(clf, {}, cv=2).fit(X, y)
    assert_false(hasattr(gs, "predict_proba"))


def test_grid_search_allows_nans():
    # Test GridSearchCV with Imputer
    X = np.arange(20, dtype=np.float64).reshape(5, -1)
    X[2, :] = np.nan
    y = [0, 0, 1, 1, 1]
    p = Pipeline([
        ('imputer', Imputer(strategy='mean', missing_values='NaN')),
        ('classifier', MockClassifier()),
    ])
    GridSearchCV(p, {'classifier__foo_param': [1, 2, 3]}, cv=2).fit(X, y)


class FailingClassifier(BaseEstimator):
    """Classifier that raises a ValueError on fit()"""

    FAILING_PARAMETER = 2

    def __init__(self, parameter=None):
        self.parameter = parameter

    def fit(self, X, y=None):
        if self.parameter == FailingClassifier.FAILING_PARAMETER:
            raise ValueError("Failing classifier failed as required")

    def predict(self, X):
        return np.zeros(X.shape[0])


def test_grid_search_failing_classifier():
    # GridSearchCV with on_error != 'raise'
    # Ensures that a warning is raised and score reset where appropriate.

    X, y = make_classification(n_samples=20, n_features=10, random_state=0)

    clf = FailingClassifier()

    # refit=False because we only want to check that errors caused by fits
    # to individual folds will be caught and warnings raised instead. If
    # refit was done, then an exception would be raised on refit and not
    # caught by grid_search (expected behavior), and this would cause an
    # error in this test.
    gs = GridSearchCV(clf, [{'parameter': [0, 1, 2]}], scoring='accuracy',
                      refit=False, error_score=0.0)
    assert_warns(FitFailedWarning, gs.fit, X, y)
    n_candidates = len(gs.cv_results_['params'])

    # Ensure that grid scores were set to zero as required for those fits
    # that are expected to fail.
    def get_cand_scores(i):
        return np.array(list(gs.cv_results_['split%d_test_score' % s][i]
                             for s in range(gs.n_splits_)))

    assert all((np.all(get_cand_scores(cand_i) == 0.0)
                for cand_i in range(n_candidates)
                if gs.cv_results_['param_parameter'][cand_i] ==
                FailingClassifier.FAILING_PARAMETER))

    gs = GridSearchCV(clf, [{'parameter': [0, 1, 2]}], scoring='accuracy',
                      refit=False, error_score=float('nan'))
    assert_warns(FitFailedWarning, gs.fit, X, y)
    n_candidates = len(gs.cv_results_['params'])
    assert all(np.all(np.isnan(get_cand_scores(cand_i)))
               for cand_i in range(n_candidates)
               if gs.cv_results_['param_parameter'][cand_i] ==
               FailingClassifier.FAILING_PARAMETER)


def test_grid_search_failing_classifier_raise():
    # GridSearchCV with on_error == 'raise' raises the error

    X, y = make_classification(n_samples=20, n_features=10, random_state=0)

    clf = FailingClassifier()

    # refit=False because we want to test the behaviour of the grid search part
    gs = GridSearchCV(clf, [{'parameter': [0, 1, 2]}], scoring='accuracy',
                      refit=False, error_score='raise')

    # FailingClassifier issues a ValueError so this is what we look for.
    assert_raises(ValueError, gs.fit, X, y)


def test_parameters_sampler_replacement():
    # raise error if n_iter too large
    params = {'first': [0, 1], 'second': ['a', 'b', 'c']}
    sampler = ParameterSampler(params, n_iter=7)
    assert_raises(ValueError, list, sampler)
    # degenerates to GridSearchCV if n_iter the same as grid_size
    sampler = ParameterSampler(params, n_iter=6)
    samples = list(sampler)
    assert_equal(len(samples), 6)
    for values in ParameterGrid(params):
        assert_true(values in samples)

    # test sampling without replacement in a large grid
    params = {'a': range(10), 'b': range(10), 'c': range(10)}
    sampler = ParameterSampler(params, n_iter=99, random_state=42)
    samples = list(sampler)
    assert_equal(len(samples), 99)
    hashable_samples = ["a%db%dc%d" % (p['a'], p['b'], p['c'])
                        for p in samples]
    assert_equal(len(set(hashable_samples)), 99)

    # doesn't go into infinite loops
    params_distribution = {'first': bernoulli(.5), 'second': ['a', 'b', 'c']}
    sampler = ParameterSampler(params_distribution, n_iter=7)
    samples = list(sampler)
    assert_equal(len(samples), 7)


def test_stochastic_gradient_loss_param():
    # Make sure the predict_proba works when loss is specified
    # as one of the parameters in the param_grid.
    param_grid = {
        'loss': ['log'],
    }
    X = np.arange(24).reshape(6, -1)
    y = [0, 0, 0, 1, 1, 1]
    clf = GridSearchCV(estimator=SGDClassifier(tol=1e-3, loss='hinge'),
                       param_grid=param_grid)

    # When the estimator is not fitted, `predict_proba` is not available as the
    # loss is 'hinge'.
    assert_false(hasattr(clf, "predict_proba"))
    clf.fit(X, y)
    clf.predict_proba(X)
    clf.predict_log_proba(X)

    # Make sure `predict_proba` is not available when setting loss=['hinge']
    # in param_grid
    param_grid = {
        'loss': ['hinge'],
    }
    clf = GridSearchCV(estimator=SGDClassifier(tol=1e-3, loss='hinge'),
                       param_grid=param_grid)
    assert_false(hasattr(clf, "predict_proba"))
    clf.fit(X, y)
    assert_false(hasattr(clf, "predict_proba"))


def test_search_train_scores_set_to_false():
    X = np.arange(6).reshape(6, -1)
    y = [0, 0, 0, 1, 1, 1]
    clf = LinearSVC(random_state=0)

    gs = GridSearchCV(clf, param_grid={'C': [0.1, 0.2]},
                      return_train_score=False)
    gs.fit(X, y)


def test_grid_search_cv_splits_consistency():
    # Check if a one time iterable is accepted as a cv parameter.
    n_samples = 100
    n_splits = 5
    X, y = make_classification(n_samples=n_samples, random_state=0)

    gs = GridSearchCV(LinearSVC(random_state=0),
                      param_grid={'C': [0.1, 0.2, 0.3]},
                      cv=OneTimeSplitter(n_splits=n_splits,
                                         n_samples=n_samples))
    gs.fit(X, y)

    gs2 = GridSearchCV(LinearSVC(random_state=0),
                       param_grid={'C': [0.1, 0.2, 0.3]},
                       cv=KFold(n_splits=n_splits))
    gs2.fit(X, y)

    # Give generator as a cv parameter
    assert_true(isinstance(KFold(n_splits=n_splits,
                                 shuffle=True, random_state=0).split(X, y),
                           GeneratorType))
    gs3 = GridSearchCV(LinearSVC(random_state=0),
                       param_grid={'C': [0.1, 0.2, 0.3]},
                       cv=KFold(n_splits=n_splits, shuffle=True,
                                random_state=0).split(X, y))
    gs3.fit(X, y)

    gs4 = GridSearchCV(LinearSVC(random_state=0),
                       param_grid={'C': [0.1, 0.2, 0.3]},
                       cv=KFold(n_splits=n_splits, shuffle=True,
                                random_state=0))
    gs4.fit(X, y)

    def _pop_time_keys(cv_results):
        for key in ('mean_fit_time', 'std_fit_time',
                    'mean_score_time', 'std_score_time'):
            cv_results.pop(key)
        return cv_results

    # Check if generators are supported as cv and
    # that the splits are consistent
    np.testing.assert_equal(_pop_time_keys(gs3.cv_results_),
                            _pop_time_keys(gs4.cv_results_))

    # OneTimeSplitter is a non-re-entrant cv where split can be called only
    # once if ``cv.split`` is called once per param setting in GridSearchCV.fit
    # the 2nd and 3rd parameter will not be evaluated as no train/test indices
    # will be generated for the 2nd and subsequent cv.split calls.
    # This is a check to make sure cv.split is not called once per param
    # setting.
    np.testing.assert_equal({k: v for k, v in gs.cv_results_.items()
                             if not k.endswith('_time')},
                            {k: v for k, v in gs2.cv_results_.items()
                             if not k.endswith('_time')})

    # Check consistency of folds across the parameters
    gs = GridSearchCV(LinearSVC(random_state=0),
                      param_grid={'C': [0.1, 0.1, 0.2, 0.2]},
                      cv=KFold(n_splits=n_splits, shuffle=True))
    gs.fit(X, y)

    # As the first two param settings (C=0.1) and the next two param
    # settings (C=0.2) are same, the test and train scores must also be
    # same as long as the same train/test indices are generated for all
    # the cv splits, for both param setting
    for score_type in ('train', 'test'):
        per_param_scores = {}
        for param_i in range(4):
            per_param_scores[param_i] = list(
                gs.cv_results_['split%d_%s_score' % (s, score_type)][param_i]
                for s in range(5))

        assert_array_almost_equal(per_param_scores[0],
                                  per_param_scores[1])
        assert_array_almost_equal(per_param_scores[2],
                                  per_param_scores[3])


def test_transform_inverse_transform_round_trip():
    clf = MockClassifier()
    grid_search = GridSearchCV(clf, {'foo_param': [1, 2, 3]}, verbose=3)

    grid_search.fit(X, y)
    X_round_trip = grid_search.inverse_transform(grid_search.transform(X))
    assert_array_equal(X, X_round_trip)
