BUG: %p not working in pd.to_datetime

[JulianWgs]

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Reproducible Example

import pandas as pd
pd.to_datetime("2/17/2022 4:16:51 PM", format="%m/%d/%Y %H:%M:%S %p")

returns

Timestamp('2022-02-17 04:16:51')

but should return

Timestamp('2022-02-17 16:16:51')

Issue Description

%p format string is ignored, when using to_datetime.It is a valid format string according to https://strftime.org/ and the pandas docs and doesn't raise an error.

Expected Behavior

The format is either parsed correctly or an error is returned that %p is not supported.

Installed Versions

INSTALLED VERSIONS

commit : 06d2301
python : 3.8.10.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.0-99-generic
Version : #112-Ubuntu SMP Thu Feb 3 13:50:55 UTC 2022
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.4.1
numpy : 1.20.3
pytz : 2021.3
dateutil : 2.8.2
pip : 22.0.3
setuptools : 50.3.2
Cython : 0.29.26
pytest : 6.2.2
hypothesis : 6.8.1
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.7.1
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.0.1
IPython : 7.30.1
pandas_datareader: None
bs4 : 4.10.0
bottleneck : None
fastparquet : None
fsspec : 2021.11.1
gcsfs : None
matplotlib : 3.5.0
numba : 0.54.1
numexpr : None
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : 4.0.0
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.7.1
sqlalchemy : None
tables : None
tabulate : 0.8.7
xarray : 0.19.0
xlrd : 2.0.1
xlwt : None
zstandard : None

[mroeschke]

This seems to match the stdlib behavior

In [1]: import datetime

In [2]: datetime.datetime.strptime("2/17/2022 4:16:51 PM", "%m/%d/%Y %H:%M:%S %p")
Out[2]: datetime.datetime(2022, 2, 17, 4, 16, 51)

[JeremyVriens]

This is expected behaviour. When you look at the Python documentation: https://docs.python.org/3/library/time.html#time.strftime it has a note on %p that says:

When used with the strptime() function, the %p directive only affects the output hour field if the %I directive is used to parse the hour.

So the correct format should be %m/%d/%Y %I:%M:%S %p (note the %H got replaced with %I, capital i) which results in:

In [1]: import datetime

In [2]: datetime.datetime.strptime("2/17/2022 4:16:51 PM", "%m/%d/%Y %I:%M:%S %p")
Out[2]: datetime.datetime(2022, 2, 17, 16, 16, 51)

I do agree that maybe Python should raise a warning when %p is used without %I in the format, however this is a discussion on Python level, not on Pandas.

[mroeschke]

Thanks closing as a usage question

[JulianWgs]

Sorry, for the inconvenience :)