Re: [I] [Python] pyarrow compute strptime not working with format '%Y%m%d %H%M%S%f' [arrow]

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

rok commented on issue #41132:
URL: https://github.com/apache/arrow/issues/41132#issuecomment-2048573219

   Thanks for reporting this @nikfio !
   This is due to [`pc.strptime`](https://arrow.apache.org/docs/dev/python/generated/pyarrow.compute.strptime.html#pyarrow-compute-strptime) using the [C/C++ format semantics](https://man7.org/linux/man-pages/man3/strptime.3.html) for parsing instead of the Python ones. Namely it seems it's the `%f` flag that is causing this issue as this works fine:
   ```python
   >>> pc.strptime('20090101 185956', format='%Y%m%d %H%M%S', unit='ms')
   <pyarrow.TimestampScalar: '2009-01-01T18:59:56.000'>
   ```
   To work around this you can try [this (cumbersome) approach] for now:
   ```python
   import pyarrow as pa
   import pyarrow.compute as pc
   ts = pa.array(["1970-01-01T00:00:59.123456789", "2000-02-29T23:23:23.999999999"], pa.string())
   ts2 = pc.strptime(pc.utf8_slice_codeunits(ts, 0, 19), format="%Y-%m-%dT%H:%M:%S", unit="ns")
   d = pc.utf8_slice_codeunits(ts, 20, 99).cast(pa.int64()).cast(pa.duration("ns"))
   pc.add(ts2, d)
   ```


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