test_from_model.py 文件源码

def test_prefit():
    """
    Test all possible combinations of the prefit parameter.
    """
    # Passing a prefit parameter with the selected model
    # and fitting a unfit model with prefit=False should give same results.
    clf = SGDClassifier(alpha=0.1, n_iter=10, shuffle=True, random_state=0)
    model = SelectFromModel(clf)
    model.fit(data, y)
    X_transform = model.transform(data)
    clf.fit(data, y)
    model = SelectFromModel(clf, prefit=True)
    assert_array_equal(model.transform(data), X_transform)

    # Check that the model is rewritten if prefit=False and a fitted model is
    # passed
    model = SelectFromModel(clf, prefit=False)
    model.fit(data, y)
    assert_array_equal(model.transform(data), X_transform)

    # Check that prefit=True and calling fit raises a ValueError
    model = SelectFromModel(clf, prefit=True)
    assert_raises(ValueError, model.fit, data, y)