[jira] [Created] (ARROW-15479) [C++] Cast to fixed size list with different field name

["Joris Van den Bossche (Jira)" <ji...@apache.org>]

Joris Van den Bossche created ARROW-15479:
---------------------------------------------

             Summary: [C++] Cast to fixed size list with different field name
                 Key: ARROW-15479
                 URL: https://issues.apache.org/jira/browse/ARROW-15479
             Project: Apache Arrow
          Issue Type: Improvement
          Components: C++
            Reporter: Joris Van den Bossche


Casting a FixedSizeListArray to a compatible type but only a different field name isn't implemented:

{code:python}
>>> my_type = pa.list_(pa.field("element", pa.int64()), 2)
>>> arr = pa.FixedSizeListArray.from_arrays(pa.array([1, 2, 3, 4, 5, 6]), 2)
>>> arr.type
FixedSizeListType(fixed_size_list<item: int64>[2])
>>> my_type
FixedSizeListType(fixed_size_list<element: int64>[2])

>>> arr.cast(my_type)
...
ArrowNotImplementedError: Unsupported cast from fixed_size_list<item: int64>[2] to fixed_size_list using function cast_fixed_size_list
{code}

While the similar operation with a variable sized list actually works:

{code:python}
>>> my_type = pa.list_(pa.field("element", pa.int64()))
>>> arr = pa.array([[1, 2], [3, 4]], pa.list_(pa.int64()))
>>> arr.type
ListType(list<item: int64>)
>>> arr.cast(my_type).type
ListType(list<element: int64>)
{code}



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