tree 0e80c7502d4b60d27cecb7f0bc63cd8e85f79fc3
parent 0c7ba1734006a69b3173758b7a7106a835b3c6c2
author Makoto Yui <myui@apache.org> 1571821311 +0900
committer Makoto Yui <myui@apache.org> 1571821311 +0900

[HIVEMALL-261][HIVEMALL-262] argmin/argmax/argsort UDF

## What changes were proposed in this pull request?

Introduce argmin/argmax/argsort UDF

## What type of PR is it?

Feature

## What is the Jira issue?

https://issues.apache.org/jira/browse/HIVEMALL-261
https://issues.apache.org/jira/browse/HIVEMALL-262

## How was this patch tested?

unit tests, manual tests on EMR

## How to use this feature?

```sql
SELECT argmax(array(5,2,0,1));
> 0

SELECT array_slice(array(5,2,0,1), argmax(array(5,2,0,1)));
> 5

SELECT argmin(array(5,2,0,1));
> 2

SELECT argsort(array(5,2,0,1));
> 2, 3, 1, 0

SELECT array_slice(array(5,2,0,1), argsort(array(5,2,0,1)));
> 0, 1, 2, 5

SELECT argsort(argsort(array(5,2,0,1))), argrank(array(5,2,0,1));
> 3, 2, 0, 1

SELECT arange(5), arange(1, 5), arange(1, 5, 1), arange(0, 5, 1);
> [0,1,2,3,4]     [1,2,3,4]       [1,2,3,4]       [0,1,2,3,4]

SELECT arange(1, 6, 2);
> 1, 3, 5

SELECT arange(-1, -6, 2);
> -1, -3, -5

SELECT argsort(array(5, 2, 0, 1)), argrank(array(5, 2, 0, 1)), argsort(argsort(array(5, 2, 0, 1)));
> [2,3,1,0]       [3,2,0,1]       [3,2,0,1]
```

## Checklist

(Please remove this section if not needed; check `x` for YES, blank for NO)

- [x] Did you apply source code formatter, i.e., `./bin/format_code.sh`, for your commit?
- [ ] Did you run system tests on Hive (or Spark)?

Author: Makoto Yui <myui@apache.org>

Closes #197 from myui/argmax.