[jira] [Assigned] (SPARK-23939) High-order function: transform_keys(map, function) → map

["Apache Spark (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-23939?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-23939:
------------------------------------

    Assignee: Apache Spark

> High-order function: transform_keys(map<K1, V>, function<K1, V, K2>) → map<K2,V>
> --------------------------------------------------------------------------------
>
>                 Key: SPARK-23939
>                 URL: https://issues.apache.org/jira/browse/SPARK-23939
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>    Affects Versions: 2.3.0
>            Reporter: Xiao Li
>            Assignee: Apache Spark
>            Priority: Major
>
> Ref: https://prestodb.io/docs/current/functions/map.html
> Returns a map that applies function to each entry of map and transforms the keys.
> {noformat}
> SELECT transform_keys(MAP(ARRAY[], ARRAY[]), (k, v) -> k + 1); -- {}
> SELECT transform_keys(MAP(ARRAY [1, 2, 3], ARRAY ['a', 'b', 'c']), (k, v) -> k + 1); -- {2 -> a, 3 -> b, 4 -> c}
> SELECT transform_keys(MAP(ARRAY ['a', 'b', 'c'], ARRAY [1, 2, 3]), (k, v) -> v * v); -- {1 -> 1, 4 -> 2, 9 -> 3}
> SELECT transform_keys(MAP(ARRAY ['a', 'b'], ARRAY [1, 2]), (k, v) -> k || CAST(v as VARCHAR)); -- {a1 -> 1, b2 -> 2}
> SELECT transform_keys(MAP(ARRAY [1, 2], ARRAY [1.0, 1.4]), -- {one -> 1.0, two -> 1.4}
>                       (k, v) -> MAP(ARRAY[1, 2], ARRAY['one', 'two'])[k]);
> {noformat}



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