diff --git a/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MulticlassMetrics.scala b/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MulticlassMetrics.scala
index 292cbaf639f90..666362ae6739a 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MulticlassMetrics.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MulticlassMetrics.scala
@@ -47,8 +47,9 @@ class MulticlassMetrics(predictionAndLabels: RDD[(Double, Double)]) {
     .collectAsMap()
   private lazy val confusions = predictionAndLabels
     .map { case (prediction, label) =>
-      ((prediction, label), 1)
-  }.reduceByKey(_ + _).collectAsMap()
+      ((label, prediction), 1)
+    }.reduceByKey(_ + _)
+    .collectAsMap()
 
   /**
    * Returns confusion matrix:
@@ -57,19 +58,18 @@ class MulticlassMetrics(predictionAndLabels: RDD[(Double, Double)]) {
    * as in "labels"
    */
   def confusionMatrix: Matrix = {
-    val transposedFlatMatrix = Array.ofDim[Double](labels.size * labels.size)
     val n = labels.size
-    var i, j = 0
-    while(i < n){
-      j = 0
-      while(j < n){
-        transposedFlatMatrix(i * labels.size + j)
-          = confusions.getOrElse((labels(i), labels(j)), 0).toDouble
+    val values = Array.ofDim[Double](n * n)
+    var i = 0
+    while (i < n) {
+      var j = 0
+      while (j < n) {
+        values(i + j * n) = confusions.getOrElse((labels(i), labels(j)), 0).toDouble
         j += 1
       }
       i += 1
     }
-    Matrices.dense(labels.size, labels.size, transposedFlatMatrix)
+    Matrices.dense(n, n, values)
   }
 
   /**
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/evaluation/MulticlassMetricsSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/evaluation/MulticlassMetricsSuite.scala
index 555343d7cdb21..1ea503971c864 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/evaluation/MulticlassMetricsSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/evaluation/MulticlassMetricsSuite.scala
@@ -17,9 +17,10 @@
 
 package org.apache.spark.mllib.evaluation
 
+import org.scalatest.FunSuite
+
 import org.apache.spark.mllib.linalg.Matrices
 import org.apache.spark.mllib.util.LocalSparkContext
-import org.scalatest.FunSuite
 
 class MulticlassMetricsSuite extends FunSuite with LocalSparkContext {
   test("Multiclass evaluation metrics") {