BUG: to_datetime - confusion with timeawarness · Issue #48678 · pandas-dev/pandas (original) (raw)

Pandas version checks

• I have checked that this issue has not already been reported.
• 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

import pandas as pd

passes

pd.to_datetime([pd.Timestamp("2022-01-01 00:00:00"), pd.Timestamp("1724-12-20 20:20:20+01:00")], utc=True)

fails

pd.to_datetime([pd.Timestamp("1724-12-20 20:20:20+01:00"), pd.Timestamp("2022-01-01 00:00:00")], utc=True) Traceback (most recent call last): File "/Users/primoz/miniconda3/envs/orange3/lib/python3.10/site-packages/IPython/core/interactiveshell.py", line 3398, in run_code exec(code_obj, self.user_global_ns, self.user_ns) File "", line 1, in <cell line: 1> pd.to_datetime([pd.Timestamp("1724-12-20 20:20:20+01:00"), pd.Timestamp("2022-01-01 00:00:00")], utc=True) File "/Users/primoz/python-projects/pandas/pandas/core/tools/datetimes.py", line 1124, in to_datetime result = convert_listlike(argc, format) File "/Users/primoz/python-projects/pandas/pandas/core/tools/datetimes.py", line 439, in _convert_listlike_datetimes result, tz_parsed = objects_to_datetime64ns( File "/Users/primoz/python-projects/pandas/pandas/core/arrays/datetimes.py", line 2182, in objects_to_datetime64ns result, tz_parsed = tslib.array_to_datetime( File "pandas/_libs/tslib.pyx", line 428, in pandas._libs.tslib.array_to_datetime File "pandas/_libs/tslib.pyx", line 535, in pandas._libs.tslib.array_to_datetime ValueError: Cannot mix tz-aware with tz-naive values

the same examples with strings only also pass

pd.to_datetime(["1724-12-20 20:20:20+01:00", "2022-01-01 00:00:00"], utc=True)

Issue Description

When calling to_datetime with pd.Timestamps in the list/series conversion fail when the datetime at position 0 is tz-aware and the other datetime is tz-naive. When datetimes are reordered the same example pass. The same example also pass when datetimes are strings.

So I am a bit confused about what is supported now. Should a case that fails work?
The error is only present in pandas==1.5.0 and in the main branch. I think it was introduced with this PR #47018.

Expected Behavior

I think to_datetime should have the same behavior in all cases.

Installed Versions

INSTALLED VERSIONS ------------------ commit : 87cfe4epython : 3.10.4.final.0 python-bits : 64 OS : Darwin OS-release : 21.6.0 Version : Darwin Kernel Version 21.6.0: Wed Aug 10 14:28:23 PDT 2022; root:xnu-8020.141.5~2/RELEASE_ARM64_T6000 machine : arm64 processor : arm byteorder : little LC_ALL : None LANG : None LOCALE : None.UTF-8 pandas : 1.5.0 numpy : 1.22.4 pytz : 2022.1 dateutil : 2.8.2 setuptools : 61.2.0 pip : 22.1.2 Cython : None pytest : None hypothesis : None sphinx : 5.1.1 blosc : None feather : None xlsxwriter : 3.0.3 lxml.etree : 4.9.1 html5lib : None pymysql : None psycopg2 : None jinja2 : 3.1.2 IPython : 8.4.0 pandas_datareader: None bs4 : 4.11.1 bottleneck : 1.3.5 brotli : None fastparquet : None fsspec : None gcsfs : None matplotlib : 3.5.2 numba : 0.56.0 numexpr : None odfpy : None openpyxl : 3.0.10 pandas_gbq : None pyarrow : None pyreadstat : None pyxlsb : None s3fs : None scipy : 1.9.1 snappy : None sqlalchemy : 1.4.39 tables : None tabulate : 0.8.10 xarray : None xlrd : 2.0.1 xlwt : None zstandard : None tzdata : 2022.2