test_categorical.py 文件源码

def test_nan_handling(self):

        # Nans are represented as -1 in labels
        s = Series(Categorical(["a", "b", np.nan, "a"]))
        self.assert_numpy_array_equal(s.cat.categories, np.array(["a", "b"]))
        self.assert_numpy_array_equal(s.values.codes, np.array([0, 1, -1, 0]))

        # If categories have nan included, the label should point to that
        # instead
        with tm.assert_produces_warning(FutureWarning):
            s2 = Series(Categorical(
                ["a", "b", np.nan, "a"], categories=["a", "b", np.nan]))
        self.assert_numpy_array_equal(s2.cat.categories, np.array(
            ["a", "b", np.nan], dtype=np.object_))
        self.assert_numpy_array_equal(s2.values.codes, np.array([0, 1, 2, 0]))

        # Changing categories should also make the replaced category np.nan
        s3 = Series(Categorical(["a", "b", "c", "a"]))
        with tm.assert_produces_warning(FutureWarning, check_stacklevel=False):
            s3.cat.categories = ["a", "b", np.nan]
        self.assert_numpy_array_equal(s3.cat.categories, np.array(
            ["a", "b", np.nan], dtype=np.object_))
        self.assert_numpy_array_equal(s3.values.codes, np.array([0, 1, 2, 0]))