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TST: added test for GH28597 #33588

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Merged
merged 4 commits into from
Apr 17, 2020
Merged

TST: added test for GH28597 #33588

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2f4ecb2
TST: added test for GH28597
Apr 16, 2020
a9d1952
fixed code formatting
Apr 16, 2020
e529e2d
moved test to pandas/tests/groupby/test_categorical.py
Apr 16, 2020
731d3c0
added blank line to please linter
Apr 17, 2020
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45 changes: 45 additions & 0 deletions pandas/tests/groupby/test_groupby.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2012,3 +2012,48 @@ def test_groups_repr_truncates(max_seq_items, expected):

result = df.groupby(np.array(df.a)).groups.__repr__()
assert result == expected


def test_sorted_missing_category_values():
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can you move this test to pandas/tests/groupby/test_categorical.py

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No problem, will do

# GH 28597
df = pd.DataFrame(
{
"foo": [
"small",
"large",
"large",
"large",
"medium",
"large",
"large",
"medium",
],
"bar": ["C", "A", "A", "C", "A", "C", "A", "C"],
}
)
df["foo"] = (
df["foo"]
.astype("category")
.cat.set_categories(["tiny", "small", "medium", "large"], ordered=True)
)

expected = pd.DataFrame(
{
"tiny": {"A": 0, "C": 0},
"small": {"A": 0, "C": 1},
"medium": {"A": 1, "C": 1},
"large": {"A": 3, "C": 2},
}
)
expected = expected.rename_axis("bar", axis="index")
expected.columns = pd.CategoricalIndex(
["tiny", "small", "medium", "large"],
categories=["tiny", "small", "medium", "large"],
ordered=True,
name="foo",
dtype="category",
)

result = df.groupby(["bar", "foo"]).size().unstack()
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I think the change in behaviour that needs to be tested is the size method and the unstack call is not relevant in the issue OP.

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There are two separate issues that have been fixed, and I think that this tests them both. One is that missing categorical values in groupby would cause the categories to become unsorted #28597 . That is the one that I have mentioned in the commit message.

The other is that previously, empty groups would be missing from the output even when grouping with categories #23865, which I think this test also catches as a side effect.

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IIUC it's the size call that is the root cause of the issues and this issue was resolved in #29690

which I think this test also catches as a side effect

maybe one of the issues should be closed as a duplicate?


tm.assert_frame_equal(result, expected)