From f2d253e8f5529cfafec815fbfc3926a45be152a6 Mon Sep 17 00:00:00 2001 From: Saehui Date: Wed, 21 Jul 2021 18:40:56 -0700 Subject: [PATCH] TST: test groupby cumcount --- pandas/tests/groupby/transform/test_transform.py | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/pandas/tests/groupby/transform/test_transform.py b/pandas/tests/groupby/transform/test_transform.py index 9062049029e4d..6275a5440a0e2 100644 --- a/pandas/tests/groupby/transform/test_transform.py +++ b/pandas/tests/groupby/transform/test_transform.py @@ -1276,3 +1276,16 @@ def test_string_rank_grouping(): result = df.groupby("A").transform("rank") expected = DataFrame({"B": [1.0, 2.0, 1.0]}) tm.assert_frame_equal(result, expected) + + +def test_transform_cumcount(): + # GH 27472 + df = DataFrame({"a": [0, 0, 0, 1, 1, 1], "b": range(6)}) + grp = df.groupby(np.repeat([0, 1], 3)) + + result = grp.cumcount() + expected = Series([0, 1, 2, 0, 1, 2]) + tm.assert_series_equal(result, expected) + + result = grp.transform("cumcount") + tm.assert_series_equal(result, expected)