Method test_join_multiindex

pandas/tests/reshape/merge/test_join.py:362–403

(self)

        d.join(a)

    def test_join_multiindex(self):
        index1 = MultiIndex.from_arrays(
            [["a", "a", "a", "b", "b", "b"], [1, 2, 3, 1, 2, 3]],
            names=["first", "second"],
        )

        index2 = MultiIndex.from_arrays(
            [["b", "b", "b", "c", "c", "c"], [1, 2, 3, 1, 2, 3]],
            names=["first", "second"],
        )

        df1 = DataFrame(
            data=np.random.default_rng(2).standard_normal(6),
            index=index1,
            columns=["var X"],
        )
        df2 = DataFrame(
            data=np.random.default_rng(2).standard_normal(6),
            index=index2,
            columns=["var Y"],
        )

        df1 = df1.sort_index(level=0)
        df2 = df2.sort_index(level=0)

        joined = df1.join(df2, how="outer")
        ex_index = Index(index1.values).union(Index(index2.values))
        expected = df1.reindex(ex_index).join(df2.reindex(ex_index))
        expected.index.names = index1.names
        tm.assert_frame_equal(joined, expected)
        assert joined.index.names == index1.names

        df1 = df1.sort_index(level=1)
        df2 = df2.sort_index(level=1)

        joined = df1.join(df2, how="outer").sort_index(level=0)
        ex_index = Index(index1.values).union(Index(index2.values))
        expected = df1.reindex(ex_index).join(df2.reindex(ex_index))
        expected.index.names = index1.names

        tm.assert_frame_equal(joined, expected)
        assert joined.index.names == index1.names

    def test_join_inner_multiindex(self, lexsorted_two_level_string_multiindex):
        key1 = ["bar", "bar", "bar", "foo", "foo", "baz", "baz", "qux", "qux", "snap"]