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From "Sean Owen (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (SPARK-28499) Optimize MinMaxScaler
Date Fri, 26 Jul 2019 13:36:00 GMT

     [ https://issues.apache.org/jira/browse/SPARK-28499?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sean Owen reassigned SPARK-28499:
---------------------------------

    Assignee: zhengruifeng

> Optimize MinMaxScaler
> ---------------------
>
>                 Key: SPARK-28499
>                 URL: https://issues.apache.org/jira/browse/SPARK-28499
>             Project: Spark
>          Issue Type: Improvement
>          Components: ML
>    Affects Versions: 3.0.0
>            Reporter: zhengruifeng
>            Assignee: zhengruifeng
>            Priority: Minor
>
> current impl of MinMaxScaler has some small places to be optimized:
> 1, avoid call param getter in udf.
> If I remember correctly, there was some tickets and prs about this, calling param getter
in udf or map function, will significantly slow down the computation.
> 2, for a constant dim, the transformed value is also a constant value, which can be precomputed.
> 3, for a usual dim (i-th), the value is update by
> values(i) = (values(i) - minArray(i)) / range(i) * scale + $(min)
> here, we can precompute  scale / range, so that a division can be skipped.



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