test_gradient_boosting.py 文件源码

def test_more_verbose_output():
    # Check verbose=2 does not cause error.
    from sklearn.externals.six.moves import cStringIO as StringIO
    import sys
    old_stdout = sys.stdout
    sys.stdout = StringIO()
    clf = GradientBoostingClassifier(n_estimators=100, random_state=1,
                                     verbose=2)
    clf.fit(X, y)
    verbose_output = sys.stdout
    sys.stdout = old_stdout

    # check output
    verbose_output.seek(0)
    header = verbose_output.readline().rstrip()
    # no OOB
    true_header = ' '.join(['%10s'] + ['%16s'] * 2) % (
        'Iter', 'Train Loss', 'Remaining Time')
    assert_equal(true_header, header)

    n_lines = sum(1 for l in verbose_output.readlines())
    # 100 lines for n_estimators==100
    assert_equal(100, n_lines)