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Posted to issues@arrow.apache.org by "AlenkaF (via GitHub)" <gi...@apache.org> on 2023/08/16 13:41:50 UTC

[GitHub] [arrow] AlenkaF opened a new issue, #37200: [Python] Converting empty table to batch results in empty list

AlenkaF opened a new issue, #37200:
URL: https://github.com/apache/arrow/issues/37200

   ### Describe the bug, including details regarding any error messages, version, and platform.
   
   When converting an empty table with a known schema to a record batch, the information about the schema is lost and the result is an empty list:
   
   ```python
   >>> my_schema = pa.schema([pa.field('col1', pa.int64())])
   >>> df = pa.table([[]], schema=my_schema)
   >>> df
   pyarrow.Table
   col1: int64
   ----
   col1: [[]]
   >>> df.to_batches()
   []
   ```
   
   but in comparison, if we are creating an empty batch with a known schema we get the following:
   ```python
   >>> batch = pa.record_batch([[]], schema=my_schema)
   >>> batch
   pyarrow.RecordBatch
   col1: int64
   ----
   col1: []
   ```
   
   and I think this should be same for the case of converting an empty table with known schema to a record batch.
   
   ### Component(s)
   
   Python


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Re: [I] [Python] Converting empty table to batch results in empty list [arrow]

Posted by "AlenkaF (via GitHub)" <gi...@apache.org>.
AlenkaF closed issue #37200: [Python] Converting empty table to batch results in empty list
URL: https://github.com/apache/arrow/issues/37200


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Re: [I] [Python] Converting empty table to batch results in empty list [arrow]

Posted by "AlenkaF (via GitHub)" <gi...@apache.org>.
AlenkaF commented on issue #37200:
URL: https://github.com/apache/arrow/issues/37200#issuecomment-1748728005

   Closing this as there is not a clear idea what to do in cases of empty tables with (can be multiple) empty chunks. Can reopen in future if we see the need to do so.


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