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Posted to issues@spark.apache.org by "zhengruifeng (JIRA)" <ji...@apache.org> on 2019/07/24 10:13:00 UTC

[jira] [Created] (SPARK-28499) Optimize MinMaxScaler

zhengruifeng created SPARK-28499:
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             Summary: 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


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 range * scale, so that a division can be skipped.



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