[jira] [Commented] (FLINK-4148) incorrect calculation distance in QuadTree

["Neelesh Srinivas Salian (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15433696#comment-15433696 ] 

Neelesh Srinivas Salian commented on FLINK-4148:
------------------------------------------------

[~humanoid], thank you for reporting this. Could you please create a Pull Request for the same patch?

> incorrect calculation distance in QuadTree
> ------------------------------------------
>
>                 Key: FLINK-4148
>                 URL: https://issues.apache.org/jira/browse/FLINK-4148
>             Project: Flink
>          Issue Type: Bug
>            Reporter: Alexey Diomin
>            Priority: Trivial
>         Attachments: 0001-FLINK-4148-incorrect-calculation-minDist-distance-in.patch
>
>
> https://github.com/apache/flink/blob/master/flink-libraries/flink-ml/src/main/scala/org/apache/flink/ml/nn/QuadTree.scala#L105
> Because EuclideanDistanceMetric extends SquaredEuclideanDistanceMetric we always move in first case and never reach case for math.sqrt(minDist)
> correct match first EuclideanDistanceMetric and after it SquaredEuclideanDistanceMetric
> p.s. because EuclideanDistanceMetric more compute expensive and stay as default DistanceMetric it's can cause some performance degradation for KNN on default parameters



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