def test_matthews_corrcoef():
rng = np.random.RandomState(0)
y_true = ["a" if i == 0 else "b" for i in rng.randint(0, 2, size=20)]
# corrcoef of same vectors must be 1
assert_almost_equal(matthews_corrcoef(y_true, y_true), 1.0)
# corrcoef, when the two vectors are opposites of each other, should be -1
y_true_inv = ["b" if i == "a" else "a" for i in y_true]
assert_almost_equal(matthews_corrcoef(y_true, y_true_inv), -1)
y_true_inv2 = label_binarize(y_true, ["a", "b"]) * -1
assert_almost_equal(matthews_corrcoef(y_true, y_true_inv2), -1)
# For the zero vector case, the corrcoef cannot be calculated and should
# result in a RuntimeWarning
mcc = assert_warns_message(RuntimeWarning, 'invalid value encountered',
matthews_corrcoef, [0, 0, 0, 0], [0, 0, 0, 0])
# But will output 0
assert_almost_equal(mcc, 0.)
# And also for any other vector with 0 variance
mcc = assert_warns_message(RuntimeWarning, 'invalid value encountered',
matthews_corrcoef, y_true,
rng.randint(-100, 100) * np.ones(20, dtype=int))
# But will output 0
assert_almost_equal(mcc, 0.)
# These two vectors have 0 correlation and hence mcc should be 0
y_1 = [1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1]
y_2 = [1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1]
assert_almost_equal(matthews_corrcoef(y_1, y_2), 0.)
# Check that sample weight is able to selectively exclude
mask = [1] * 10 + [0] * 10
# Now the first half of the vector elements are alone given a weight of 1
# and hence the mcc will not be a perfect 0 as in the previous case
assert_raises(AssertionError, assert_almost_equal,
matthews_corrcoef(y_1, y_2, sample_weight=mask), 0.)
评论列表
文章目录
