[ARROW-13772] [R] Binding for median() and quantile() aggregation functions

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 6.0.0
• Component/s: R
• Labels: kernel pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/29399
• Assignee: Ian Cook
• Reporter: Nicola Crane
• Created: 26/Aug/21 18:27
• Updated: 11/Jan/23 08:35
• Resolved: 25/Sep/21 00:23

Description

Another aggregate function we’ll need to look at is median().

That should in theory map to the existing quantile kernel and the hopefully-coming-soon hash_quantile kernel with q = 0.5, but that will not work right now for several reasons (see https://issues.apache.org/jira/browse/ARROW-13309).

However we also have a pair of
approximate quantile kernels: tdigest and hash_tdigest that we could map median() to.

Issue Links

• blocks: ARROW-13618 [R] Use Arrow engine for summarize() by default
• depends upon: ARROW-13520 [C++] Implement hash_aggregate approximate quantile kernel
• is blocked by: ARROW-12669 [C++] Kernel to return Array of elements at index of list in ListArray
• is blocked by: ARROW-14050 [C++] tdigest, quantile return empty arrays when nulls not skipped
• is blocked by: ARROW-14052 [C++] Add appx_median, hash_appx_median functions
• is blocked by: ARROW-13740 [R] summarize() should not eagerly evaluate
• is related to: ARROW-14021 [R] Bind median() and quantile() to exact not approximate median and quantile
• links to: GitHub Pull Request #11018