def test_mutual_info_classif():
X, y = make_classification(n_samples=100,
n_features=5,
n_informative=1,
n_redundant=1,
n_repeated=0,
n_classes=2,
n_clusters_per_class=1,
flip_y=0.0,
class_sep=10,
shuffle=False,
random_state=0)
# Test in KBest mode.
univariate_filter = SelectKBest(mutual_info_classif, k=2)
X_r = univariate_filter.fit(X, y).transform(X)
X_r2 = GenericUnivariateSelect(mutual_info_classif, mode='k_best',
param=2).fit(X, y).transform(X)
assert_array_equal(X_r, X_r2)
support = univariate_filter.get_support()
gtruth = np.zeros(5)
gtruth[:2] = 1
assert_array_equal(support, gtruth)
# Test in Percentile mode.
univariate_filter = SelectPercentile(mutual_info_classif, percentile=40)
X_r = univariate_filter.fit(X, y).transform(X)
X_r2 = GenericUnivariateSelect(mutual_info_classif,
mode='percentile',
param=40).fit(X, y).transform(X)
assert_array_equal(X_r, X_r2)
support = univariate_filter.get_support()
gtruth = np.zeros(5)
gtruth[:2] = 1
assert_array_equal(support, gtruth)
def test_mutual_info_regression():
X, y = make_regression(n_samples=100,
n_features=10,
n_informative=2,
shuffle=False,
random_state=0,
noise=10)
# Test in KBest mode.
univariate_filter = SelectKBest(mutual_info_regression, k=2)
X_r = univariate_filter.fit(X, y).transform(X)
assert_best_scores_kept(univariate_filter)
X_r2 = GenericUnivariateSelect(mutual_info_regression,
mode='k_best',
param=2).fit(X, y).transform(X)
assert_array_equal(X_r, X_r2)
support = univariate_filter.get_support()
gtruth = np.zeros(10)
gtruth[:2] = 1
assert_array_equal(support, gtruth)
# Test in Percentile mode.
univariate_filter = SelectPercentile(mutual_info_regression, percentile=20)
X_r = univariate_filter.fit(X, y).transform(X)
X_r2 = GenericUnivariateSelect(mutual_info_regression,
mode='percentile',
param=20).fit(X, y).transform(X)
assert_array_equal(X_r, X_r2)
support = univariate_filter.get_support()
gtruth = np.zeros(10)
gtruth[:2] = 1
assert_array_equal(support, gtruth)
def test_boundary_case_ch2():
# Test boundary case, and always aim to select 1 feature.
X = np.array([[10, 20], [20, 20], [20, 30]])
y = np.array([[1], [0], [0]])
scores, pvalues = chi2(X, y)
assert_array_almost_equal(scores, np.array([4., 0.71428571]))
assert_array_almost_equal(pvalues, np.array([0.04550026, 0.39802472]))
filter_fdr = SelectFdr(chi2, alpha=0.1)
filter_fdr.fit(X, y)
support_fdr = filter_fdr.get_support()
assert_array_equal(support_fdr, np.array([True, False]))
filter_kbest = SelectKBest(chi2, k=1)
filter_kbest.fit(X, y)
support_kbest = filter_kbest.get_support()
assert_array_equal(support_kbest, np.array([True, False]))
filter_percentile = SelectPercentile(chi2, percentile=50)
filter_percentile.fit(X, y)
support_percentile = filter_percentile.get_support()
assert_array_equal(support_percentile, np.array([True, False]))
filter_fpr = SelectFpr(chi2, alpha=0.1)
filter_fpr.fit(X, y)
support_fpr = filter_fpr.get_support()
assert_array_equal(support_fpr, np.array([True, False]))
filter_fwe = SelectFwe(chi2, alpha=0.1)
filter_fwe.fit(X, y)
support_fwe = filter_fwe.get_support()
assert_array_equal(support_fwe, np.array([True, False]))
def test_select_kbest_classif():
# Test whether the relative univariate feature selection
# gets the correct items in a simple classification problem
# with the k best heuristic
X, y = make_classification(n_samples=200,
n_features=20,
n_informative=3,
n_redundant=2,
n_repeated=0,
n_classes=8,
n_clusters_per_class=1,
flip_y=0.0,
class_sep=10,
shuffle=False,
random_state=0)
univariate_filter = SelectKBest(f_classif, k=5)
X_r = univariate_filter.fit(X, y).transform(X)
X_r2 = GenericUnivariateSelect(f_classif, mode='k_best',
param=5).fit(X, y).transform(X)
assert_array_equal(X_r, X_r2)
support = univariate_filter.get_support()
gtruth = np.zeros(20)
gtruth[:5] = 1
assert_array_equal(support, gtruth)
def test_select_kbest_zero():
# Test whether k=0 correctly returns no features.
X, y = make_classification(n_samples=20,
n_features=10,
shuffle=False,
random_state=0)
univariate_filter = SelectKBest(f_classif, k=0)
univariate_filter.fit(X, y)
support = univariate_filter.get_support()
gtruth = np.zeros(10, dtype=bool)
assert_array_equal(support, gtruth)
X_selected = assert_warns_message(UserWarning, 'No features were selected',
univariate_filter.transform, X)
assert X_selected.shape == (20, 0)
def test_select_kbest_regression():
# Test whether the relative univariate feature selection
# gets the correct items in a simple regression problem
# with the k best heuristic
X, y = make_regression(n_samples=200,
n_features=20,
n_informative=5,
shuffle=False,
random_state=0,
noise=10)
univariate_filter = SelectKBest(f_regression, k=5)
X_r = univariate_filter.fit(X, y).transform(X)
assert_best_scores_kept(univariate_filter)
X_r2 = GenericUnivariateSelect(f_regression, mode='k_best',
param=5).fit(X, y).transform(X)
assert_array_equal(X_r, X_r2)
support = univariate_filter.get_support()
gtruth = np.zeros(20)
gtruth[:5] = 1
assert_array_equal(support, gtruth)
plt.bar(X_indices - .25,
svm_weights,
width=.2,
label='SVM weight',
color='navy',
edgecolor='black')
clf_selected = make_pipeline(SelectKBest(f_classif, k=4), MinMaxScaler(),
LinearSVC())
clf_selected.fit(X_train, y_train)
print('Classification accuracy after univariate feature selection: {:.3f}'.
format(clf_selected.score(X_test, y_test)))
svm_weights_selected = np.abs(clf_selected[-1].coef_).sum(axis=0)
svm_weights_selected /= svm_weights_selected.sum()
plt.bar(X_indices[selector.get_support()] - .05,
svm_weights_selected,
width=.2,
label='SVM weights after selection',
color='c',
edgecolor='black')
plt.title("Comparing feature selection")
plt.xlabel('Feature number')
plt.yticks(())
plt.axis('tight')
plt.legend(loc='upper right')
plt.show()