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
import datetime
period = '15s'
df = pd.DataFrame([["80000000", 1],
["80101000", 100]],
columns=["Time", "Value"])
df['DateTime'] = df['Time'].apply(lambda s: datetime.datetime.strptime(str(s), '%H%M%S%f'))
df.set_index('DateTime', inplace=True)
df["Value"] = df["Value"].astype('uint64')
df_rs = df['Value'].resample(period)
print(df_rs.first())Issue Description
fail to access the first value of an resampled series with unit64 dtype . If dtype is changed to uint32 or int, the ouput is correct.
errors
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\resample.py", line 1028, in f
return self._downsample(_method, min_count=min_count)
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\resample.py", line 1190, in _downsample
result = obj.groupby(self.grouper, axis=self.axis).aggregate(how, **kwargs)
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\generic.py", line 265, in aggregate
return getattr(self, func)(*args, **kwargs)
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\groupby.py", line 2241, in first
return self._agg_general(
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\groupby.py", line 1506, in _agg_general
result = self._cython_agg_general(
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\groupby.py", line 1592, in _cython_agg_general
new_mgr = data.grouped_reduce(array_func, ignore_failures=True)
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\internals\base.py", line 199, in grouped_reduce
res = func(arr)
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\groupby.py", line 1578, in array_func
result = self.grouper._cython_operation(
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\ops.py", line 939, in _cython_operation
return cy_op.cython_operation(
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\ops.py", line 626, in cython_operation
return self._cython_op_ndim_compat(
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\ops.py", line 451, in _cython_op_ndim_compat
res = self._call_cython_op(
File "C:\Users\86138\anaconda3\lib\site-packages\pandas\core\groupby\ops.py", line 544, in _call_cython_op
func(result, counts, values, comp_ids, min_count)
File "pandas_libs\groupby.pyx", line 1140, in pandas._libs.groupby.group_nth
RuntimeError: empty group with uint64_t
Expected Behavior
DateTime
1900-01-01 08:00:00 1.0
1900-01-01 08:00:15 NaN
1900-01-01 08:00:30 NaN
1900-01-01 08:00:45 NaN
1900-01-01 08:01:00 100.0
Freq: 15S, Name: Value, dtype: float64
Installed Versions
pandas : 1.4.2
numpy : 1.19.3
pytz : 2021.1
dateutil : 2.8.1
pip : 21.0.1
setuptools : 52.0.0.post20210125
Cython : 0.29.23
pytest : 6.2.3
hypothesis : None
sphinx : 4.0.1
blosc : None
feather : None
xlsxwriter : 1.3.8
lxml.etree : 4.6.3
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 2.11.3
IPython : 7.22.0
pandas_datareader: 0.10.0
bs4 : 4.9.3
bottleneck : 1.3.2
brotli :
fastparquet : None
fsspec : 0.9.0
gcsfs : None
markupsafe : 1.1.1
matplotlib : 3.3.4
numba : 0.53.1
numexpr : 2.7.3
odfpy : None
openpyxl : 3.0.7
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.6.2
snappy : None
sqlalchemy : 1.4.7
tables : 3.6.1
tabulate : 0.8.9
xarray : None
xlrd : 2.0.1
xlwt : 1.3.0
zstandard : None
None