Repository: spark
Updated Branches:
  refs/heads/master cd81fc9e8 -> 021dafc6a


[SPARK-12026][MLLIB] ChiSqTest gets slower and slower over time when number of 
features is large

jira: https://issues.apache.org/jira/browse/SPARK-12026

The issue is valid as features.toArray.view.zipWithIndex.slice(startCol, 
endCol) becomes slower as startCol gets larger.

I tested on local and the change can improve the performance and the running 
time was stable.

Author: Yuhao Yang <hhb...@gmail.com>

Closes #10146 from hhbyyh/chiSq.


Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/021dafc6
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/021dafc6
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/021dafc6

Branch: refs/heads/master
Commit: 021dafc6a05a31dc22c9f9110dedb47a1f913087
Parents: cd81fc9
Author: Yuhao Yang <hhb...@gmail.com>
Authored: Wed Jan 13 17:43:27 2016 -0800
Committer: Joseph K. Bradley <jos...@databricks.com>
Committed: Wed Jan 13 17:43:27 2016 -0800

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 .../scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala     | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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http://git-wip-us.apache.org/repos/asf/spark/blob/021dafc6/mllib/src/main/scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala
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diff --git 
a/mllib/src/main/scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala 
b/mllib/src/main/scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala
index f22f2df..4a3fb064 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala
@@ -109,7 +109,9 @@ private[stat] object ChiSqTest extends Logging {
           }
           i += 1
           distinctLabels += label
-          features.toArray.view.zipWithIndex.slice(startCol, endCol).map { 
case (feature, col) =>
+          val brzFeatures = features.toBreeze
+          (startCol until endCol).map { col =>
+            val feature = brzFeatures(col)
             allDistinctFeatures(col) += feature
             (col, feature, label)
           }
@@ -122,7 +124,7 @@ private[stat] object ChiSqTest extends Logging {
           pairCounts.keys.filter(_._1 == 
startCol).map(_._3).toArray.distinct.zipWithIndex.toMap
       }
       val numLabels = labels.size
-      pairCounts.keys.groupBy(_._1).map { case (col, keys) =>
+      pairCounts.keys.groupBy(_._1).foreach { case (col, keys) =>
         val features = keys.map(_._2).toArray.distinct.zipWithIndex.toMap
         val numRows = features.size
         val contingency = new BDM(numRows, numLabels, new 
Array[Double](numRows * numLabels))


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