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BUG: SeriesGroupBy.apply sets name attribute if result is DataFrame #49907
Description
Pandas version checks
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I have checked that this issue has not already been reported.
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I have confirmed this bug exists on the latest version of pandas.
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I have confirmed this bug exists on the main branch of pandas.
Reproducible Example
def f(piece):
return DataFrame({"value": piece, "demeaned": piece - piece.mean()})
df = pd.DataFrame({'a': [1,2,3], 'b': [4, 5, 5]})
res = df.groupby('a')['b'].apply(f)
print(res.name)Issue Description
This prints 'b'. But .name shouldn't be an attribute of DataFrame...
Expected Behavior
AttributeError: 'DataFrame' object has no attribute 'name'
Installed Versions
Details
INSTALLED VERSIONS
commit : 3b09765
python : 3.8.15.final.0
python-bits : 64
OS : Linux
OS-release : 5.10.102.1-microsoft-standard-WSL2
Version : #1 SMP Wed Mar 2 00:30:59 UTC 2022
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_GB.UTF-8
LOCALE : en_GB.UTF-8
pandas : 2.0.0.dev0+759.g3b09765bc9
numpy : 1.23.5
pytz : 2022.6
dateutil : 2.8.2
setuptools : 65.5.1
pip : 22.3.1
Cython : 0.29.32
pytest : 7.2.0
hypothesis : 6.58.0
sphinx : 4.5.0
blosc : None
feather : None
xlsxwriter : 3.0.3
lxml.etree : 4.9.1
html5lib : 1.1
pymysql : 1.0.2
psycopg2 : 2.9.3
jinja2 : 3.0.3
IPython : 8.6.0
pandas_datareader: 0.10.0
bs4 : 4.11.1
bottleneck : 1.3.5
brotli :
fastparquet : 2022.11.0
fsspec : 2021.11.0
gcsfs : 2021.11.0
matplotlib : 3.6.2
numba : 0.56.4
numexpr : 2.8.3
odfpy : None
openpyxl : 3.0.10
pandas_gbq : 0.17.9
pyarrow : 9.0.0
pyreadstat : 1.2.0
pyxlsb : 1.0.10
s3fs : 2021.11.0
scipy : 1.9.3
snappy :
sqlalchemy : 1.4.44
tables : 3.7.0
tabulate : 0.9.0
xarray : 2022.11.0
xlrd : 2.0.1
zstandard : 0.19.0
tzdata : None
qtpy : None
pyqt5 : None
None
Activity
MarcoGorelli commentedon Nov 25, 2022
This was fine in
1.4.4, so I'm labelling it as a regression[-]BUG: groupby apply (lambda ...: DataFrame) sets `name` attribute[/-][+] BUG: SeriesGroupBy.apply sets name attribute if result is DataFrame[/+]MarcoGorelli commentedon Nov 25, 2022
Looks like this was caused by #46623
cc @ma3da (just FYI, no blame!)
ma3da commentedon Nov 29, 2022
👌 Still, sorry for the glitch!