284 lines
10 KiB
Python
284 lines
10 KiB
Python
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import pytest
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import numpy as np
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import scipy.sparse as sp
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import warnings
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from sklearn.preprocessing import KBinsDiscretizer
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from sklearn.preprocessing import OneHotEncoder
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from sklearn.utils._testing import (
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assert_array_almost_equal,
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assert_array_equal,
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assert_warns_message
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)
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X = [[-2, 1.5, -4, -1],
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[-1, 2.5, -3, -0.5],
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[0, 3.5, -2, 0.5],
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[1, 4.5, -1, 2]]
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@pytest.mark.parametrize(
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'strategy, expected',
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[('uniform', [[0, 0, 0, 0], [1, 1, 1, 0], [2, 2, 2, 1], [2, 2, 2, 2]]),
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('kmeans', [[0, 0, 0, 0], [0, 0, 0, 0], [1, 1, 1, 1], [2, 2, 2, 2]]),
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('quantile', [[0, 0, 0, 0], [1, 1, 1, 1], [2, 2, 2, 2], [2, 2, 2, 2]])])
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def test_fit_transform(strategy, expected):
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est = KBinsDiscretizer(n_bins=3, encode='ordinal', strategy=strategy)
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est.fit(X)
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assert_array_equal(expected, est.transform(X))
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def test_valid_n_bins():
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KBinsDiscretizer(n_bins=2).fit_transform(X)
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KBinsDiscretizer(n_bins=np.array([2])[0]).fit_transform(X)
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assert KBinsDiscretizer(n_bins=2).fit(X).n_bins_.dtype == np.dtype(np.int)
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def test_invalid_n_bins():
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est = KBinsDiscretizer(n_bins=1)
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err_msg = ("KBinsDiscretizer received an invalid "
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"number of bins. Received 1, expected at least 2.")
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with pytest.raises(ValueError, match=err_msg):
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est.fit_transform(X)
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est = KBinsDiscretizer(n_bins=1.1)
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err_msg = ("KBinsDiscretizer received an invalid "
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"n_bins type. Received float, expected int.")
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with pytest.raises(ValueError, match=err_msg):
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est.fit_transform(X)
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def test_invalid_n_bins_array():
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# Bad shape
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n_bins = np.full((2, 4), 2.)
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est = KBinsDiscretizer(n_bins=n_bins)
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err_msg = r"n_bins must be a scalar or array of shape \(n_features,\)."
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with pytest.raises(ValueError, match=err_msg):
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est.fit_transform(X)
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# Incorrect number of features
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n_bins = [1, 2, 2]
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est = KBinsDiscretizer(n_bins=n_bins)
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err_msg = r"n_bins must be a scalar or array of shape \(n_features,\)."
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with pytest.raises(ValueError, match=err_msg):
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est.fit_transform(X)
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# Bad bin values
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n_bins = [1, 2, 2, 1]
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est = KBinsDiscretizer(n_bins=n_bins)
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err_msg = ("KBinsDiscretizer received an invalid number of bins "
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"at indices 0, 3. Number of bins must be at least 2, "
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"and must be an int.")
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with pytest.raises(ValueError, match=err_msg):
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est.fit_transform(X)
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# Float bin values
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n_bins = [2.1, 2, 2.1, 2]
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est = KBinsDiscretizer(n_bins=n_bins)
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err_msg = ("KBinsDiscretizer received an invalid number of bins "
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"at indices 0, 2. Number of bins must be at least 2, "
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"and must be an int.")
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with pytest.raises(ValueError, match=err_msg):
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est.fit_transform(X)
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@pytest.mark.parametrize(
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'strategy, expected',
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[('uniform', [[0, 0, 0, 0], [0, 1, 1, 0], [1, 2, 2, 1], [1, 2, 2, 2]]),
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('kmeans', [[0, 0, 0, 0], [0, 0, 0, 0], [1, 1, 1, 1], [1, 2, 2, 2]]),
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('quantile', [[0, 0, 0, 0], [0, 1, 1, 1], [1, 2, 2, 2], [1, 2, 2, 2]])])
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def test_fit_transform_n_bins_array(strategy, expected):
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est = KBinsDiscretizer(n_bins=[2, 3, 3, 3], encode='ordinal',
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strategy=strategy).fit(X)
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assert_array_equal(expected, est.transform(X))
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# test the shape of bin_edges_
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n_features = np.array(X).shape[1]
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assert est.bin_edges_.shape == (n_features, )
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for bin_edges, n_bins in zip(est.bin_edges_, est.n_bins_):
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assert bin_edges.shape == (n_bins + 1, )
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def test_invalid_n_features():
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est = KBinsDiscretizer(n_bins=3).fit(X)
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bad_X = np.arange(25).reshape(5, -1)
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err_msg = "Incorrect number of features. Expecting 4, received 5"
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with pytest.raises(ValueError, match=err_msg):
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est.transform(bad_X)
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@pytest.mark.parametrize('strategy', ['uniform', 'kmeans', 'quantile'])
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def test_same_min_max(strategy):
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warnings.simplefilter("always")
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X = np.array([[1, -2],
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[1, -1],
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[1, 0],
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[1, 1]])
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est = KBinsDiscretizer(strategy=strategy, n_bins=3, encode='ordinal')
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assert_warns_message(UserWarning,
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"Feature 0 is constant and will be replaced "
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"with 0.", est.fit, X)
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assert est.n_bins_[0] == 1
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# replace the feature with zeros
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Xt = est.transform(X)
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assert_array_equal(Xt[:, 0], np.zeros(X.shape[0]))
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def test_transform_1d_behavior():
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X = np.arange(4)
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est = KBinsDiscretizer(n_bins=2)
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with pytest.raises(ValueError):
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est.fit(X)
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est = KBinsDiscretizer(n_bins=2)
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est.fit(X.reshape(-1, 1))
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with pytest.raises(ValueError):
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est.transform(X)
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@pytest.mark.parametrize('i', range(1, 9))
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def test_numeric_stability(i):
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X_init = np.array([2., 4., 6., 8., 10.]).reshape(-1, 1)
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Xt_expected = np.array([0, 0, 1, 1, 1]).reshape(-1, 1)
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# Test up to discretizing nano units
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X = X_init / 10**i
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Xt = KBinsDiscretizer(n_bins=2, encode='ordinal').fit_transform(X)
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assert_array_equal(Xt_expected, Xt)
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def test_invalid_encode_option():
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est = KBinsDiscretizer(n_bins=[2, 3, 3, 3], encode='invalid-encode')
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err_msg = (r"Valid options for 'encode' are "
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r"\('onehot', 'onehot-dense', 'ordinal'\). "
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r"Got encode='invalid-encode' instead.")
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with pytest.raises(ValueError, match=err_msg):
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est.fit(X)
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def test_encode_options():
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est = KBinsDiscretizer(n_bins=[2, 3, 3, 3],
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encode='ordinal').fit(X)
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Xt_1 = est.transform(X)
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est = KBinsDiscretizer(n_bins=[2, 3, 3, 3],
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encode='onehot-dense').fit(X)
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Xt_2 = est.transform(X)
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assert not sp.issparse(Xt_2)
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assert_array_equal(OneHotEncoder(
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categories=[np.arange(i) for i in [2, 3, 3, 3]],
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sparse=False)
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.fit_transform(Xt_1), Xt_2)
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est = KBinsDiscretizer(n_bins=[2, 3, 3, 3],
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encode='onehot').fit(X)
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Xt_3 = est.transform(X)
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assert sp.issparse(Xt_3)
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assert_array_equal(OneHotEncoder(
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categories=[np.arange(i) for i in [2, 3, 3, 3]],
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sparse=True)
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.fit_transform(Xt_1).toarray(),
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Xt_3.toarray())
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def test_invalid_strategy_option():
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est = KBinsDiscretizer(n_bins=[2, 3, 3, 3], strategy='invalid-strategy')
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err_msg = (r"Valid options for 'strategy' are "
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r"\('uniform', 'quantile', 'kmeans'\). "
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r"Got strategy='invalid-strategy' instead.")
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with pytest.raises(ValueError, match=err_msg):
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est.fit(X)
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@pytest.mark.parametrize(
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'strategy, expected_2bins, expected_3bins, expected_5bins',
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[('uniform', [0, 0, 0, 0, 1, 1], [0, 0, 0, 0, 2, 2], [0, 0, 1, 1, 4, 4]),
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('kmeans', [0, 0, 0, 0, 1, 1], [0, 0, 1, 1, 2, 2], [0, 0, 1, 2, 3, 4]),
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('quantile', [0, 0, 0, 1, 1, 1], [0, 0, 1, 1, 2, 2], [0, 1, 2, 3, 4, 4])])
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def test_nonuniform_strategies(
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strategy, expected_2bins, expected_3bins, expected_5bins):
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X = np.array([0, 0.5, 2, 3, 9, 10]).reshape(-1, 1)
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# with 2 bins
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est = KBinsDiscretizer(n_bins=2, strategy=strategy, encode='ordinal')
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Xt = est.fit_transform(X)
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assert_array_equal(expected_2bins, Xt.ravel())
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# with 3 bins
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est = KBinsDiscretizer(n_bins=3, strategy=strategy, encode='ordinal')
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Xt = est.fit_transform(X)
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assert_array_equal(expected_3bins, Xt.ravel())
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# with 5 bins
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est = KBinsDiscretizer(n_bins=5, strategy=strategy, encode='ordinal')
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Xt = est.fit_transform(X)
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assert_array_equal(expected_5bins, Xt.ravel())
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@pytest.mark.parametrize(
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'strategy, expected_inv',
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[('uniform', [[-1.5, 2., -3.5, -0.5], [-0.5, 3., -2.5, -0.5],
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[0.5, 4., -1.5, 0.5], [0.5, 4., -1.5, 1.5]]),
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('kmeans', [[-1.375, 2.125, -3.375, -0.5625],
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[-1.375, 2.125, -3.375, -0.5625],
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[-0.125, 3.375, -2.125, 0.5625],
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[0.75, 4.25, -1.25, 1.625]]),
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('quantile', [[-1.5, 2., -3.5, -0.75], [-0.5, 3., -2.5, 0.],
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[0.5, 4., -1.5, 1.25], [0.5, 4., -1.5, 1.25]])])
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@pytest.mark.parametrize('encode', ['ordinal', 'onehot', 'onehot-dense'])
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def test_inverse_transform(strategy, encode, expected_inv):
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kbd = KBinsDiscretizer(n_bins=3, strategy=strategy, encode=encode)
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Xt = kbd.fit_transform(X)
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Xinv = kbd.inverse_transform(Xt)
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assert_array_almost_equal(expected_inv, Xinv)
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@pytest.mark.parametrize('strategy', ['uniform', 'kmeans', 'quantile'])
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def test_transform_outside_fit_range(strategy):
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X = np.array([0, 1, 2, 3])[:, None]
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kbd = KBinsDiscretizer(n_bins=4, strategy=strategy, encode='ordinal')
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kbd.fit(X)
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X2 = np.array([-2, 5])[:, None]
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X2t = kbd.transform(X2)
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assert_array_equal(X2t.max(axis=0) + 1, kbd.n_bins_)
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assert_array_equal(X2t.min(axis=0), [0])
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def test_overwrite():
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X = np.array([0, 1, 2, 3])[:, None]
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X_before = X.copy()
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est = KBinsDiscretizer(n_bins=3, encode="ordinal")
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Xt = est.fit_transform(X)
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assert_array_equal(X, X_before)
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Xt_before = Xt.copy()
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Xinv = est.inverse_transform(Xt)
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assert_array_equal(Xt, Xt_before)
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assert_array_equal(Xinv, np.array([[0.5], [1.5], [2.5], [2.5]]))
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@pytest.mark.parametrize(
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'strategy, expected_bin_edges',
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[('quantile', [0, 1, 3]), ('kmeans', [0, 1.5, 3])])
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def test_redundant_bins(strategy, expected_bin_edges):
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X = [[0], [0], [0], [0], [3], [3]]
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kbd = KBinsDiscretizer(n_bins=3, strategy=strategy)
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msg = ("Bins whose width are too small (i.e., <= 1e-8) in feature 0 "
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"are removed. Consider decreasing the number of bins.")
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assert_warns_message(UserWarning, msg, kbd.fit, X)
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assert_array_almost_equal(kbd.bin_edges_[0], expected_bin_edges)
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def test_percentile_numeric_stability():
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X = np.array([0.05, 0.05, 0.95]).reshape(-1, 1)
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bin_edges = np.array([0.05, 0.23, 0.41, 0.59, 0.77, 0.95])
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Xt = np.array([0, 0, 4]).reshape(-1, 1)
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kbd = KBinsDiscretizer(n_bins=10, encode='ordinal',
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strategy='quantile')
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msg = ("Bins whose width are too small (i.e., <= 1e-8) in feature 0 "
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"are removed. Consider decreasing the number of bins.")
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assert_warns_message(UserWarning, msg, kbd.fit, X)
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assert_array_almost_equal(kbd.bin_edges_[0], bin_edges)
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assert_array_almost_equal(kbd.transform(X), Xt)
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