[jira] [Assigned] (SPARK-22451) Reduce decision tree aggregate size for unordered features from O(2^numCategories) to O(numCategories)

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

     [ https://issues.apache.org/jira/browse/SPARK-22451?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-22451:
------------------------------------

    Assignee:     (was: Apache Spark)

> Reduce decision tree aggregate size for unordered features from O(2^numCategories) to O(numCategories)
> ------------------------------------------------------------------------------------------------------
>
>                 Key: SPARK-22451
>                 URL: https://issues.apache.org/jira/browse/SPARK-22451
>             Project: Spark
>          Issue Type: Improvement
>          Components: ML
>    Affects Versions: 2.2.0
>            Reporter: Weichen Xu
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> Do not need generate all possible splits for unordered features before aggregate,
> in aggregete (executor side):
> 1. Change `mixedBinSeqOp`, for each unordered feature, we do the same stat with ordered features. so for unordered features, we only need O(numCategories) space for this feature stat.
> 2. After driver side get the aggregate result, generate all possible split combinations, and compute the best split.
> This will reduce decision tree aggregate size for each unordered feature from O(2^numCategories) to O(numCategories),  `numCategories` is the arity of this unordered feature.
> This also reduce the cpu cost in executor side. Reduce time complexity for this unordered feature from O(numPoints * 2^numCategories) to O(numPoints).
> This won't increase time complexity for unordered features best split computing in driver side.



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org