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https://issues.apache.org/jira/browse/ARROW-17989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17615821#comment-17615821
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Joris Van den Bossche commented on ARROW-17989:
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This seems somewhat duplicate / related to ARROW-17141 (cc [~rokm]
[~lidavidm]), although I don't fully understand why that was closed. David
mentioned:
> Yeah, if the Python bindings convert names to indices that makes sense.
I suppose if you call "struct_field" directly on an actual StructArray, it's
indeed the binding that could do this string name -> index conversion (although
it currently does not do that). But if you use this with expressions, at the
moment when constructing the expression (eg with
{{pc.struct_field(pc.field("my_struct"), ["my_field"])}} you don't know the
schema and can't convert the field name to index.
It _seems_ relatively straightforward in the kernel itself to also work with
string field names (getting the index would be a
{{struct_array->type->GetFieldIndex(name)}} away), unless I am missing some
consequences?
> [C++] Enable struct_field kernel to accept string field names
> -------------------------------------------------------------
>
> Key: ARROW-17989
> URL: https://issues.apache.org/jira/browse/ARROW-17989
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Joris Van den Bossche
> Priority: Major
> Labels: compute
>
> Currently the "struct_field" kernel only works for integer indices for the
> child fields. From the StructFieldOption class
> (https://github.com/apache/arrow/blob/3d7f2f22a0fc441a41b8fa971e11c0f4290ebb24/cpp/src/arrow/compute/api_scalar.h#L283-L285):
> {code}
> /// The child indices to extract. For instance, to get the 2nd child
> /// of the 1st child of a struct or union, this would be {0, 1}.
> std::vector<int> indices;
> {code}
> It would be nice if you could also refer to fields by name in addition to by
> position.
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