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API: transform behaves differently with 'ffill' on DataFrameGroupBy and SeriesGroupBy #39638

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Merged
merged 4 commits into from
Feb 15, 2021
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API: transform behaves differently with 'ffill' on DataFrameGroupBy and SeriesGroupBy #39638

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9945eb7
pandas-dev issue #24211
ftrihardjo Feb 7, 2021
4080287
pandas-dev issue #24211
ftrihardjo Feb 8, 2021
f68b82b
pandas-dev issue #24211
ftrihardjo Feb 12, 2021
1099913
pandas-dev issue #24211
ftrihardjo Feb 12, 2021
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10 changes: 10 additions & 0 deletions pandas/tests/groupby/transform/test_transform.py
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Original file line number Diff line number Diff line change
Expand Up @@ -938,6 +938,16 @@ def test_any_all_np_func(func):
tm.assert_series_equal(res, exp)


def test_transform_ffill():
# GH 24211
data = [["a", 0.0], ["a", float("nan")], ["b", 1.0], ["b", float("nan")]]
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can you co-locate with other ffill/filling tests (in this file)

df = DataFrame(data, columns=["key", "values"])
tm.assert_series_equal(
df.groupby("key").transform("ffill")["values"],
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can you use
result=
expected=

df.groupby("key")["values"].transform("ffill"),
)

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test both for seriesgropuby & dataframegroupby


def test_groupby_transform_rename():
# https://github.com/pandas-dev/pandas/issues/23461
def demean_rename(x):
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