[ARROW-15736] [C++] Aggregate functions for min and max index.

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: C++
• Labels: kernel
• External issue URL: https://github.com/apache/arrow/issues/31184
• Assignee: Unassigned
• Reporter: A. Coady
• Created: 20/Feb/22 23:17
• Updated: 11/Jan/23 11:39

Description

Numpy and Pandas both have `argmin` and `argmax`, for the common use case of finding values in parallel arrays which correspond to min or max values. Proposals:

• `min_max_index` for arrays
• `hash_min_max_index` for aggregations
• some ability to break ties:
  • `min_max_index` for tables with multiple sort keys, similar to `sort_indices`
  • `min_max_indices` for arrays to match all equal values