[FLINK-4148] incorrect calculation distance in QuadTree

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.2.0, 1.3.0
• Component/s: Library / Machine Learning
• Assignee: Unassigned
• Reporter: Alexey Diomin
• Created: 04/Jul/16 12:34
• Updated: 13/Apr/21 20:40
• Resolved: 06/Jan/17 15:46

Description

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

Issue Links

• links to: GitHub Pull Request #2442