From 5416aa31715fbabd1f6991c13f639f7f22d90c1b Mon Sep 17 00:00:00 2001 From: smithto1 Date: Fri, 31 Jul 2020 11:37:52 +0100 Subject: [PATCH] adding test for #18451 --- pandas/tests/groupby/test_groupby.py | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/pandas/tests/groupby/test_groupby.py b/pandas/tests/groupby/test_groupby.py index ebce5b0ef0a66..8c51ebf89f5c0 100644 --- a/pandas/tests/groupby/test_groupby.py +++ b/pandas/tests/groupby/test_groupby.py @@ -2055,3 +2055,17 @@ def test_groups_repr_truncates(max_seq_items, expected): result = df.groupby(np.array(df.a)).groups.__repr__() assert result == expected + + +def test_group_on_two_row_multiindex_returns_one_tuple_key(): + # GH 18451 + df = pd.DataFrame([{"a": 1, "b": 2, "c": 99}, {"a": 1, "b": 2, "c": 88}]) + df = df.set_index(["a", "b"]) + + grp = df.groupby(["a", "b"]) + result = grp.indices + expected = {(1, 2): np.array([0, 1], dtype=np.int64)} + + assert len(result) == 1 + key = (1, 2) + assert (result[key] == expected[key]).all()