8000 FIX explicit exception message for strict selectors · scikit-learn/scikit-learn@99f0044 · GitHub
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FIX explicit exception message for strict selectors
1 parent 1d08f08 commit 99f0044

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+25
-3
lines changed

3 files changed

+25
-3
lines changed

‎sklearn/feature_selection/base.py

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Original file line numberDiff line numberDiff line change
@@ -73,6 +73,9 @@ def transform(self, X):
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"""
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X = check_array(X, accept_sparse='csr')
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mask = self.get_support()
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if not mask.any():
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raise ValueError("No features were selected: either the data is"
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" too noisy or the selection test too strict.")
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if len(mask) != X.shape[1]:
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raise ValueError("X has a different shape than during fitting.")
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return check_array(X, accept_sparse='csr')[:, safe_mask(X, mask)]

‎sklearn/feature_selection/tests/test_feature_select.py

Lines changed: 18 additions & 1 deletion
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@@ -9,6 +9,7 @@
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from sklearn.utils.testing import assert_equal
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from sklearn.utils.testing import assert_almost_equal
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from sklearn.utils.testing import assert_raises
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from sklearn.utils.testing import assert_raise_message
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from sklearn.utils.testing import assert_true
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from sklearn.utils.testing import assert_array_equal
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from sklearn.utils.testing import assert_array_almost_equal
@@ -251,10 +252,12 @@ def test_select_kbest_zero():
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shuffle=False, random_state=0)
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univariate_filter = SelectKBest(f_classif, k=0)
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univariate_filter.fit(X, y).transform(X)
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univariate_filter.fit(X, y)
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support = univariate_filter.get_support()
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gtruth = np.zeros(10, dtype=bool)
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assert_array_equal(support, gtruth)
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assert_raise_message(ValueError, 'No features were selected',
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univariate_filter.transform, X)
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def test_select_fpr_classif():
@@ -585,3 +588,17 @@ def test_f_classif_constant_feature():
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X, y = make_classification(n_samples=10, n_features=5)
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X[:, 0] = 2.0
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assert_warns(UserWarning, f_classif, X, y)
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def test_no_feature_selected():
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rng = np.random.RandomState(0)
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# Generate random uncorrelated data: a strict univariate test should
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# rejects all the features
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X = rng.rand(40, 10)
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y = rng.randint(0, 4, size=40)
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fdr = SelectFdr(alpha=0.00001).fit(X, y)
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assert_array_equal(fdr.get_support(), np.zeros(10))
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assert_raise_message(ValueError, 'No features were selected',
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fdr.transform, X)

‎sklearn/feature_selection/univariate_selection.py

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -496,8 +496,10 @@ def _get_support_mask(self):
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alpha = self.alpha
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sv = np.sort(self.pvalues_)
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threshold = sv[sv < alpha * np.arange(len(self.pvalues_))].max()
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return self.pvalues_ <= threshold
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selected = sv[sv < alpha * np.arange(len(self.pvalues_))]
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if selected.size == 0:
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return np.zeros_like(self.pvalues_, dtype=bool)
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return self.pvalues_ <= selected.max()
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class SelectFwe(_BaseFilter):

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