test_ranking.py 文件源码

def test_roc_curve_one_label():
    y_true = [1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
    y_pred = [0, 1, 0, 1, 0, 1, 0, 1, 0, 1]
    # assert there are warnings
    w = UndefinedMetricWarning
    fpr, tpr, thresholds = assert_warns(w, roc_curve, y_true, y_pred)
    # all true labels, all fpr should be nan
    assert_array_equal(fpr,
                       np.nan * np.ones(len(thresholds)))
    assert_equal(fpr.shape, tpr.shape)
    assert_equal(fpr.shape, thresholds.shape)

    # assert there are warnings
    fpr, tpr, thresholds = assert_warns(w, roc_curve,
                                        [1 - x for x in y_true],
                                        y_pred)
    # all negative labels, all tpr should be nan
    assert_array_equal(tpr,
                       np.nan * np.ones(len(thresholds)))
    assert_equal(fpr.shape, tpr.shape)
    assert_equal(fpr.shape, thresholds.shape)