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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
import pandas as pd
dates = pd.DatetimeIndex(['2022-01-01', '2022-01-02', '2022-01-04']) # missing a day
df = pd.DataFrame([0, 1, 2], index=dates)
df.resample("D")[0].idxmax() # raises value errorIssue Description
When using resample with idxmax/idxmin it will raise a ValueError if a period is missing.
Python traceback
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/groupby/groupby.py", line 950, in wrapper
return self._python_apply_general(curried, self._obj_with_exclusions)
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/groupby/groupby.py", line 1455, in _python_apply_general
values, mutated = self.grouper.apply(f, data, self.axis)
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/groupby/ops.py", line 761, in apply
res = f(group)
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/groupby/groupby.py", line 939, in curried
return f(x, *args, **kwargs)
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/series.py", line 2404, in idxmax
i = self.argmax(axis, skipna, *args, **kwargs)
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/base.py", line 657, in argmax
return nanops.nanargmax( # type: ignore[return-value]
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/nanops.py", line 93, in _f
return f(*args, **kwargs)
File "/home/shh/miniconda3/envs/pandas_test/lib/python3.8/site-packages/pandas/core/nanops.py", line 1096, in nanargmax
result = values.argmax(axis) # type: ignore[var-annotated]
ValueError: attempt to get argmax of an empty sequence
A small thing, I noticed while filling out this bug report was I could not get pd.show_versions() to work before I downgraded setuptools<60.
Expected Behavior
I would expect it to return NaT instead of a ValueError like:
df.resample("D")[0].apply(lambda x: x.idxmax() if len(x) else None)
Installed Versions
Show versions
INSTALLED VERSIONS
------------------
commit : 4bfe3d07b4858144c219b9346329027024102ab6
python : 3.8.13.final.0
python-bits : 64
OS : Linux
OS-release : 5.17.5-76051705-generic
Version : #202204271406~1653440576~22.04~6277a18 SMP PREEMPT Wed May 25 01
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8
pandas : 1.4.2
numpy : 1.22.4
pytz : 2022.1
dateutil : 2.8.2
pip : 22.1.2
setuptools : 59.8.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.4.0
pandas_datareader: None
bs4 : 4.11.1
bottleneck : None
brotli :
fastparquet : None
fsspec : None
gcsfs : None
markupsafe : 2.1.1
matplotlib : None
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : None
snappy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
zstandard : None