[GitHub] [spark] srowen commented on a change in pull request #28045: [SPARK-31283][ML] Simplify ChiSq by adding a common method

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srowen commented on a change in pull request #28045: [SPARK-31283][ML] Simplify ChiSq by adding a common method
URL: https://github.com/apache/spark/pull/28045#discussion_r399821160
 
 

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 File path: mllib/src/main/scala/org/apache/spark/mllib/stat/test/ChiSqTest.scala
 ##########
 @@ -94,127 +94,73 @@ private[spark] object ChiSqTest extends Logging {
       methodName: String = PEARSON.name): Array[ChiSqTestResult] = {
     data.flatMap { case LabeledPoint(label, features) =>
       require(features.size == numFeatures)
-      features.iterator.map { case (col, value) =>
-        (col, (value, label))
-      }
+      features.iterator.map { case (col, value) => (col, (label, value)) }
     }.aggregateByKey(new OpenHashMap[(Double, Double), Long])(
-      seqOp = { case (count, t) =>
-        count.changeValue(t, 1L, _ + 1L)
-        count
+      seqOp = { case (counts, t) =>
+        counts.changeValue(t, 1L, _ + 1L)
+        counts
       },
-      combOp = { case (count1, count2) =>
-        count2.iterator.foreach { case (t, c) =>
-          count1.changeValue(t, c, _ + c)
-        }
-        count1
-      }
-    ).map { case (col, count) =>
-      val label2Index = count.iterator.map(_._1._2).toArray.distinct.sorted.zipWithIndex.toMap
-      val numLabels = label2Index.size
-      if (numLabels > maxCategories) {
-        throw new SparkException(s"Chi-square test expect factors (categorical values) but "
-          + s"found more than $maxCategories distinct label values.")
-      }
-
-      val value2Index = count.iterator.map(_._1._1).toArray.distinct.sorted.zipWithIndex.toMap
-      val numValues = value2Index.size
-      if (numValues > maxCategories) {
-        throw new SparkException(s"Chi-square test expect factors (categorical values) but "
-          + s"found more than $maxCategories distinct values in column $col.")
+      combOp = { case (counts1, counts2) =>
+        counts2.foreach { case (t, c) => counts1.changeValue(t, c, _ + c) }
 
 Review comment:
   OK, so the iterator isn't helping here if just used with foreach. OK.

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