BUG: ValueError on ".transform" method applied to an empty DataFrame #39636
Labels
Apply
Apply, Aggregate, Transform
Regression
Functionality that used to work in a prior pandas version
Milestone
I have checked that this issue has not already been reported.
I have confirmed this bug exists on the latest version of pandas.
(optional) I have confirmed this bug exists on the master branch of pandas.
Code Sample, a copy-pastable example
Output on version 1.1.5:
Output on version 1.2.x:
Problem description
Applying
.transform
on an empty DataFrame raises aValueError
on version 1.2.x. This is a change on the behavior of 1.1.5 version that returns the same empty DataFrame (as.apply
is still doing).The change that added this error apparently is related to this commit 7b6ab94
Expected Output
Output of
pd.show_versions()
INSTALLED VERSIONS
commit : 9d598a5
python : 3.9.1.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.0-65-generic
Version : #73-Ubuntu SMP Mon Jan 18 17:25:17 UTC 2021
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8
pandas : 1.2.1
numpy : 1.20.0
pytz : 2021.1
dateutil : 2.8.1
pip : 20.2.3
setuptools : 49.2.1
Cython : None
pytest : 6.2.2
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.6.2
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : None
IPython : 7.20.0
pandas_datareader: None
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyxlsb : None
s3fs : None
scipy : 1.6.0
sqlalchemy : 1.3.23
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None
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