Can a struct be aggregated with 'list' on a table.group_by?

[robhod]

Describe the usage question you have. Please include as many useful details as possible.

I'm trying to create a list of structs based on a grouping column. See below:
Hitting not implemented error but hash_list docs (https://arrow.apache.org/docs/cpp/compute.html#aggregations) suggest it supports any input type so wasn't sure if there was an issue in how I set this up or if I should raise a feature request/bug?

import pyarrow as pa

# source data
table = pa.table(
    {
        "col1": [1, 1, 2, 2, 3],
        "struct_col": [
            {"a": 1, "b": "testa"},
            {"a": 1, "b": "testb"},
            {"a": 2, "b": "testc"},
            {"a": 2, "b": "testd"},
            {"a": 3, "b": "teste"},
        ],
    }
)

# required output
grouped_table = pa.table(
    {
        "grouped": [1, 2, 3],
        "agg_struct_col": [
            [{"a": 1, "b": "testa"}, {"a": 1, "b": "testb"}],
            [{"a": 2, "b": "testc"}, {"a": 2, "b": "testd"}],
            [{"a": 3, "b": "teste"}],
        ],
    }
)

# using group_by
grouped = table.group_by("col1").aggregate([("struct_col", "list")])

File "scratch/pyarrowexample.py", line 30, in
grouped = table.group_by("col1").aggregate([("struct_col", "hash_list")])
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "pyarrow/table.pxi", line 6359, in pyarrow.lib.TableGroupBy.aggregate
File "l/.venv/lib/python3.11/site-packages/pyarrow/acero.py", line 403, in _group_by
return decl.to_table(use_threads=use_threads)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "pyarrow/_acero.pyx", line 590, in pyarrow._acero.Declaration.to_table
File "pyarrow/error.pxi", line 155, in pyarrow.lib.pyarrow_internal_check_status
File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status
pyarrow.lib.ArrowNotImplementedError: Function 'hash_list' has no kernel matching input types (struct<a: int64, b: string>, uint32)

Component(s)

Python