[ARROW-10640] [C++] An "if_else" kernel to combine two arrays based on a mask

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/26596
• Assignee: Niranda Perera
• Reporter: Joris Van den Bossche
• Created: 18/Nov/20 10:04
• Updated: 11/Jan/23 08:14
• Resolved: 03/Jun/21 18:19

Description

(from discussion in ARROW-9489 with maartenbreddels)

A general "where" kernel like np.where (https://numpy.org/doc/stable/reference/generated/numpy.where.html) seems a generally useful kernel to have, and could also help mimicking some other python (setitem-like) operations.

The concrete use case in ARROW-9489 is to basically do a fill_null(array[string], array[string]) which could be expressed as where(is_null(arr), arr2, arr).

Issue Links

• is a parent of: ARROW-12955 [C++] Add additional type support for if_else kernel
• is a parent of: ARROW-12975 [C++][Python] if_else kernel doesn't support upcasting
• is depended upon by: ARROW-12964 [R] Add bindings for ifelse() and if_else()
• is related to: ARROW-11044 [C++] Add "replace" kernel
• relates to: ARROW-13220 [C++] Add a 'choose' kernel/scalar compute function
• supercedes: ARROW-11044 [C++] Add "replace" kernel
• links to: GitHub Pull Request #10377
• links to: GitHub Pull Request #10410