BUG: inconsistent None handling for ISO and non-ISO formats · Issue #50071 · pandas-dev/pandas (original) (raw)

Pandas version checks

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• 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 [15]: to_datetime(['2020-01-01 00:00:00+01:00', '2020-01-01 00:00:00+02:00', None], format='%Y-%m-%d %H:%M:%S%z') Out[15]: Index([2020-01-01 00:00:00+01:00, 2020-01-01 00:00:00+02:00, None], dtype='object')

In [16]: to_datetime(['2020-01-01 00:00:00+01:00', '2020-01-01 00:00:00+02:00', None], format='%Y-%d-%m %H:%M:%S%z') Out[16]: Index([2020-01-01 00:00:00+01:00, 2020-01-01 00:00:00+02:00, NaT], dtype='object')

Issue Description

In the first (ISO) case, None stays None. But in the second (non-ISO) case, None becomes NaT.

Expected Behavior

@jbrockmendel any thoughts on what should be correct?

I think I'd prefer the latter (just change to NaT)

Installed Versions

INSTALLED VERSIONS

commit : 8dab54d
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 : 1.5.2
numpy : 1.23.5
pytz : 2022.6
dateutil : 2.8.2
setuptools : 65.5.1
pip : 22.3.1
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 : 8.6.0
pandas_datareader: None
bs4 : 4.11.1
bottleneck : None
brotli : None
fastparquet : None
fsspec : None
gcsfs : None
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
tzdata : None
None