test_bagging.py 文件源码

def test_probability():
    # Predict probabilities.
    rng = check_random_state(0)
    X_train, X_test, y_train, y_test = train_test_split(iris.data,
                                                        iris.target,
                                                        random_state=rng)

    with np.errstate(divide="ignore", invalid="ignore"):
        # Normal case
        ensemble = BaggingClassifier(base_estimator=DecisionTreeClassifier(),
                                     random_state=rng).fit(X_train, y_train)

        assert_array_almost_equal(np.sum(ensemble.predict_proba(X_test),
                                         axis=1),
                                  np.ones(len(X_test)))

        assert_array_almost_equal(ensemble.predict_proba(X_test),
                                  np.exp(ensemble.predict_log_proba(X_test)))

        # Degenerate case, where some classes are missing
        ensemble = BaggingClassifier(base_estimator=LogisticRegression(),
                                     random_state=rng,
                                     max_samples=5).fit(X_train, y_train)

        assert_array_almost_equal(np.sum(ensemble.predict_proba(X_test),
                                         axis=1),
                                  np.ones(len(X_test)))

        assert_array_almost_equal(ensemble.predict_proba(X_test),
                                  np.exp(ensemble.predict_log_proba(X_test)))