[jira] [Created] (ARROW-15839) [Python] Allow to reconstruct a ListArray with ListArray.from_arrays and keep the nulls

["quentin lhoest (Jira)" <ji...@apache.org>]

quentin lhoest created ARROW-15839:
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             Summary: [Python] Allow to reconstruct a ListArray with ListArray.from_arrays and keep the nulls
                 Key: ARROW-15839
                 URL: https://issues.apache.org/jira/browse/ARROW-15839
             Project: Apache Arrow
          Issue Type: Improvement
          Components: Python
    Affects Versions: 7.0.0
            Reporter: quentin lhoest


Hi ! Right now when one wants to reconstruct a ListArray using ListArrar.from_arrays, the `null` values may be lost:
{code:java}
import pyarrow as pa

arr = pa.array([None, [0]])
reconstructed_arr = pa.ListArray.from_arrays(arr.offsets, arr.values)
print(reconstructed_arr.to_pylist())
# [[], [0]] {code}
It would be nice to have a `mask` parameter to `ListArray.from_arrays` (or any way to provide the validity bitmap) to be able to reconstruct the original array with the `null` values.

It would also be consistent with `StructArray.from_arrays` that already has the `mask` parameter.



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