[GitHub] [arrow] MarcoGorelli commented on issue #15047: [Python] Drop pytz for timezone support (default to use datetime.timezone / zoneinfo)

["MarcoGorelli (via GitHub)" <gi...@apache.org>]

MarcoGorelli commented on issue #15047:
URL: https://github.com/apache/arrow/issues/15047#issuecomment-1592523553

   Does it really fall back to pytz?
   
   I don't have pytz installed:
   ```console
   $ python -c 'import pytz'
   Traceback (most recent call last):
     File "<string>", line 1, in <module>
   ModuleNotFoundError: No module named 'pytz'
   ```
   but trying to convert `2038-04-01 09:00` from 'America/Boise' to UTC, and I'm getting the same (wrong) result with pyarrow as I would with pandas:
   ```python
   import pyarrow as pa
   import pyarrow.compute as pc
   
   from datetime import datetime, timezone
   from zoneinfo import ZoneInfo
   
   string = '2038-04-01 03:00:00.000000'
   
   dt = datetime.fromisoformat(string)
   dt = dt.replace(tzinfo=ZoneInfo('America/Boise'))
   tz = ZoneInfo('UTC')
   converted_dt = dt.astimezone(tz)
   print(converted_dt)
   
   ts = pc.assume_timezone(pa.array([datetime(2038, 4, 1, 3)]), timezone='America/Boise')
   print(ts)
   ```
   
   This outputs
   ```python
   2038-04-01 09:00:00+00:00
   [
     2038-04-01 10:00:00.000000
   ]
   ```
   whereas I was expecting
   ```python
   2038-04-01 09:00:00+00:00
   [
     2038-04-01 09:00:00.000000
   ]
   ```
   
   Is there a way to "force" zoneinfo usage?
   
   I think this is what's causing issues when converting polars to pandas: https://github.com/pola-rs/polars/issues/9315


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