Pandas version checks

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  • [X] I have confirmed this bug exists on the latest version of pandas.

  • [ ] I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

In [1]: import pandas as pd

In [2]: s = pd.Series(["2020-05-31 08:00:00", "2000-12-31 04:00:05", "1800-03-14 07:30:20"], dtype='datetime64[ms]')

In [3]: s
Out[3]: 
0   2020-05-31 08:00:00
1   2000-12-31 04:00:05
2   1800-03-14 07:30:20
dtype: datetime64[ms]

In [4]: s.dt.round('U')
/nvme/0/pgali/envs/cudfdev/lib/python3.10/site-packages/pandas/core/arrays/datetimelike.py:2006: RuntimeWarning: divide by zero encountered in divmod
  result_i8 = round_nsint64(values, mode, nanos)
Out[4]: 
0   1970-01-01
1   1970-01-01
2   1970-01-01
dtype: datetime64[ms]

Issue Description

Performing a rounding operation of resolution lesser than the dtype, or when there is sub-second data and the rounding resolution is a sub-second data should ideally be a no-op. Instead we seem to be running into division by zero scenario and returning incorrect results.

Expected Behavior

In [3]: s.dt.round('U')
Out[3]: 
0   2020-05-31 08:00:00
1   2000-12-31 04:00:05
2   1800-03-14 07:30:20
dtype: datetime64[ms]

Installed Versions

In [5]: pd.show_versions() /nvme/0/pgali/envs/cudfdev/lib/python3.10/site-packages/_distutils_hack/__init__.py:33: UserWarning: Setuptools is replacing distutils. warnings.warn("Setuptools is replacing distutils.") INSTALLED VERSIONS ------------------ commit : 478d340667831908b5b4bf09a2787a11a14560c9 python : 3.10.10.final.0 python-bits : 64 OS : Linux OS-release : 4.15.0-76-generic Version : #86-Ubuntu SMP Fri Jan 17 17:24:28 UTC 2020 machine : x86_64 processor : x86_64 byteorder : little LC_ALL : None LANG : en_US.UTF-8 LOCALE : en_US.UTF-8 pandas : 2.0.0 numpy : 1.23.5 pytz : 2023.3 dateutil : 2.8.2 setuptools : 67.6.1 pip : 23.1 Cython : 0.29.34 pytest : 7.3.1 hypothesis : 6.72.0 sphinx : 5.3.0 blosc : None feather : None xlsxwriter : None lxml.etree : None html5lib : None pymysql : None psycopg2 : None jinja2 : 3.1.2 IPython : 8.12.0 pandas_datareader: None bs4 : 4.12.2 bottleneck : None brotli : fastparquet : None fsspec : 2023.4.0 gcsfs : None matplotlib : None numba : 0.56.4 numexpr : None odfpy : None openpyxl : None pandas_gbq : None pyarrow : 11.0.0 pyreadstat : None pyxlsb : None s3fs : 2023.4.0 scipy : 1.10.1 snappy : sqlalchemy : 1.4.46 tables : None tabulate : 0.9.0 xarray : None xlrd : None zstandard : None tzdata : 2023.3 qtpy : None pyqt5 : None

Comment From: galipremsagar

cc: @mroeschke

Comment From: jbrockmendel

on main this raises ZeroDivisionError, which is at least slightly better than silently giving incorrect results. PR to fix this would be welcome.

Comment From: Lokeshrathi

If someone is working on this, can we please connect and work on this. As I am a newbie here and would love to learn and explore pandas, since I use it on a day-to-day basis.

I am fine with any hour of the day. :-)