tests for multiclass classification

Author: manishamde

mllib/src/main/scala/org/apache/spark/mllib/tree/DecisionTree.scala

@@ -1003,8 +1003,6 @@ object DecisionTree extends Serializable with Logging {
     val numBins = if (maxBins <= count) maxBins else count.toInt
     logDebug("numBins = " + numBins)
 
-    // TODO: Multiclass modification here
-
     /*
      * Ensure #bins is always greater than the categories. For multiclass classification,
      * #bins should be greater than 2^(maxCategories - 1) - 1.
@@ -1058,17 +1056,18 @@ object DecisionTree extends Serializable with Logging {
 
             // Use different bin/split calculation strategy for multiclass classification
             if (strategy.isMultiClassification) {
-              // Iterate from 1 to 2^maxFeatureValue leading to 2^(maxFeatureValue- 1) - 1
+              // Iterate from 0 to 2^maxFeatureValue - 1 leading to 2^(maxFeatureValue- 1) - 1
               // combinations.
-              var index = 1
-              while (index < math.pow(2.0, maxFeatureValue).toInt) {
-                val categories: List[Double] = extractMultiClassCategories(index, maxFeatureValue)
+              var index = 0
+              while (index < math.pow(2.0, maxFeatureValue).toInt - 1) {
+                val categories: List[Double]
+                  = extractMultiClassCategories(index + 1, maxFeatureValue)
                 splits(featureIndex)(index)
                   = new Split(featureIndex, Double.MinValue, Categorical, categories)
                 bins(featureIndex)(index) = {
                   if (index == 0) {
                     new Bin(new DummyCategoricalSplit(featureIndex, Categorical),
-                      splits(featureIndex)(0), Categorical, index)
+                      splits(featureIndex)(0), Categorical, Double.MinValue)
                   } else {
                     new Bin(splits(featureIndex)(index-1), splits(featureIndex)(index), Categorical,
                       Double.MinValue)
@@ -1147,19 +1146,24 @@ object DecisionTree extends Serializable with Logging {
   }
 
   /**
-   * Nested method to extract list of eligible categories given an index
+   * Nested method to extract list of eligible categories given an index. It extracts the
+   * position of ones in a binary representation of the input. If binary
+   * representation of an number is 01101 (13), the output list should (3.0, 2.0,
+   * 0.0). The maxFeatureValue depict the number of rightmost digits that will be tested for ones.
    */
-  private def extractMultiClassCategories(i: Int, maxFeatureValue: Double): List[Double] = {
-    // TODO: Test this
+  private[tree] def extractMultiClassCategories(
+      input: Int,
+      maxFeatureValue: Int): List[Double] = {
     var categories = List[Double]()
     var j = 0
+    var bitShiftedInput = input
     while (j < maxFeatureValue) {
-      var copy = i
-      if (copy % 2 != 0) {
+      if (bitShiftedInput % 2 != 0) {
         // updating the list of categories.
         categories = j.toDouble :: categories
       }
-      copy = copy >> 1
+      //Right shift by one
+      bitShiftedInput = bitShiftedInput >> 1
       j += 1
     }
     categories

mllib/src/test/scala/org/apache/spark/mllib/tree/DecisionTreeSuite.scala

@@ -231,6 +231,120 @@ class DecisionTreeSuite extends FunSuite with LocalSparkContext {
     assert(bins(1)(3) === null)
   }
 
+  test("extract categories from a number for multiclass classification") {
+    val l = DecisionTree.extractMultiClassCategories(13, 10)
+    assert(l.length === 3)
+    assert(List(3.0, 2.0, 0.0).toSeq == l.toSeq)
+  }
+
+  test("split and bin calculations for categorical variables wiht multiclass classification") {
+    val arr = DecisionTreeSuite.generateCategoricalDataPoints()
+    assert(arr.length === 1000)
+    val rdd = sc.parallelize(arr)
+    val strategy = new Strategy(
+      Classification,
+      Gini,
+      maxDepth = 3,
+      maxBins = 100,
+      categoricalFeaturesInfo = Map(0 -> 2, 1-> 2),
+      numClassesForClassification = 3)
+    val (splits, bins) = DecisionTree.findSplitsBins(rdd, strategy)
+
+    // Expecting 2^3 - 1 = 7 bins/splits
+    assert(splits(0)(0).feature === 0)
+    assert(splits(0)(0).threshold === Double.MinValue)
+    assert(splits(0)(0).featureType === Categorical)
+    assert(splits(0)(0).categories.length === 1)
+    assert(splits(0)(0).categories.contains(0.0))
+    assert(splits(1)(0).feature === 1)
+    assert(splits(1)(0).threshold === Double.MinValue)
+    assert(splits(1)(0).featureType === Categorical)
+    assert(splits(1)(0).categories.length === 1)
+    assert(splits(1)(0).categories.contains(0.0))
+
+    assert(splits(0)(1).feature === 0)
+    assert(splits(0)(1).threshold === Double.MinValue)
+    assert(splits(0)(1).featureType === Categorical)
+    assert(splits(0)(1).categories.length === 1)
+    assert(splits(0)(1).categories.contains(1.0))
+    assert(splits(1)(1).feature === 1)
+    assert(splits(1)(1).threshold === Double.MinValue)
+    assert(splits(1)(1).featureType === Categorical)
+    assert(splits(1)(1).categories.length === 1)
+    assert(splits(1)(1).categories.contains(1.0))
+
+    assert(splits(0)(2).feature === 0)
+    assert(splits(0)(2).threshold === Double.MinValue)
+    assert(splits(0)(2).featureType === Categorical)
+    assert(splits(0)(2).categories.length === 2)
+    assert(splits(0)(2).categories.contains(0.0))
+    assert(splits(0)(2).categories.contains(1.0))
+    assert(splits(1)(2).feature === 1)
+    assert(splits(1)(2).threshold === Double.MinValue)
+    assert(splits(1)(2).featureType === Categorical)
+    assert(splits(1)(2).categories.length === 2)
+    assert(splits(1)(2).categories.contains(0.0))
+    assert(splits(1)(2).categories.contains(1.0))
+
+    assert(splits(0)(3) === null)
+
+
+    // Check bins.
+
+    assert(bins(0)(0).category === Double.MinValue)
+    assert(bins(0)(0).lowSplit.categories.length === 0)
+    assert(bins(0)(0).highSplit.categories.length === 1)
+    assert(bins(0)(0).highSplit.categories.contains(0.0))
+    assert(bins(1)(0).category === Double.MinValue)
+    assert(bins(1)(0).lowSplit.categories.length === 0)
+    assert(bins(1)(0).highSplit.categories.length === 1)
+    assert(bins(1)(0).highSplit.categories.contains(0.0))
+
+    assert(bins(0)(1).category === Double.MinValue)
+    assert(bins(0)(1).lowSplit.categories.length === 1)
+    assert(bins(0)(1).lowSplit.categories.contains(0.0))
+    assert(bins(0)(1).highSplit.categories.length === 1)
+    assert(bins(0)(1).highSplit.categories.contains(1.0))
+    assert(bins(1)(1).category === Double.MinValue)
+    assert(bins(1)(1).lowSplit.categories.length === 1)
+    assert(bins(1)(1).lowSplit.categories.contains(0.0))
+    assert(bins(1)(1).highSplit.categories.length === 1)
+    assert(bins(1)(1).highSplit.categories.contains(1.0))
+
+    assert(bins(0)(2).category === Double.MinValue)
+    assert(bins(0)(2).lowSplit.categories.length === 1)
+    assert(bins(0)(2).lowSplit.categories.contains(1.0))
+    assert(bins(0)(2).highSplit.categories.length === 2)
+    assert(bins(0)(2).highSplit.categories.contains(1.0))
+    assert(bins(0)(2).highSplit.categories.contains(0.0))
+    assert(bins(1)(2).category === Double.MinValue)
+    assert(bins(1)(2).lowSplit.categories.length === 1)
+    assert(bins(1)(2).lowSplit.categories.contains(1.0))
+    assert(bins(1)(2).highSplit.categories.length === 2)
+    assert(bins(1)(2).highSplit.categories.contains(1.0))
+    assert(bins(1)(2).highSplit.categories.contains(0.0))
+
+    assert(bins(0)(3) === null)
+    assert(bins(1)(3) === null)
+
+  }
+
+  test("split and bin calculations for categorical variables with no sample for one category " +
+    "for multiclass classification") {
+    val arr = DecisionTreeSuite.generateCategoricalDataPoints()
+    assert(arr.length === 1000)
+    val rdd = sc.parallelize(arr)
+    val strategy = new Strategy(
+      Classification,
+      Gini,
+      maxDepth = 3,
+      maxBins = 100,
+      categoricalFeaturesInfo = Map(0 -> 3, 1-> 3),
+      numClassesForClassification = 3)
+    val (splits, bins) = DecisionTree.findSplitsBins(rdd, strategy)
+
+  }
+
   test("classification stump with all categorical variables") {
     val arr = DecisionTreeSuite.generateCategoricalDataPoints()
     assert(arr.length === 1000)
@@ -430,29 +544,29 @@ class DecisionTreeSuite extends FunSuite with LocalSparkContext {
 
 object DecisionTreeSuite {
 
-  def generateOrderedLabeledPointsWithLabel0(): Array[LabeledPoint] = {
-    val arr = new Array[LabeledPoint](1000)
+  def generateOrderedLabeledPointsWithLabel0(): Array[WeightedLabeledPoint] = {
+    val arr = new Array[WeightedLabeledPoint](1000)
     for (i <- 0 until 1000) {
-      val lp = new LabeledPoint(0.0, Vectors.dense(i.toDouble, 1000.0 - i))
+      val lp = new WeightedLabeledPoint(0.0, Vectors.dense(i.toDouble, 1000.0 - i))
       arr(i) = lp
     }
     arr
   }
 
-  def generateOrderedLabeledPointsWithLabel1(): Array[LabeledPoint] = {
-    val arr = new Array[LabeledPoint](1000)
+  def generateOrderedLabeledPointsWithLabel1(): Array[WeightedLabeledPoint] = {
+    val arr = new Array[WeightedLabeledPoint](1000)
     for (i <- 0 until 1000) {
-      val lp = new LabeledPoint(1.0, Vectors.dense(i.toDouble, 999.0 - i))
+      val lp = new WeightedLabeledPoint(1.0, Vectors.dense(i.toDouble, 999.0 - i))
       arr(i) = lp
     }
     arr
   }
 
-  def generateOrderedLabeledPoints(): Array[LabeledPoint] = {
-    val arr = new Array[LabeledPoint](1000)
+  def generateOrderedLabeledPoints(): Array[WeightedLabeledPoint] = {
+    val arr = new Array[WeightedLabeledPoint](1000)
     for (i <- 0 until 1000) {
       if (i < 600) {
-        val lp = new LabeledPoint(0.0, Vectors.dense(i.toDouble, 1000.0 - i))
+        val lp = new WeightedLabeledPoint(0.0, Vectors.dense(i.toDouble, 1000.0 - i))
         arr(i) = lp
       } else {
         val lp = new WeightedLabeledPoint(1.0, Vectors.dense(i.toDouble, 1000.0 - i))
@@ -462,11 +576,11 @@ object DecisionTreeSuite {
     arr
   }
 
-  def generateCategoricalDataPoints(): Array[LabeledPoint] = {
-    val arr = new Array[LabeledPoint](1000)
+  def generateCategoricalDataPoints(): Array[WeightedLabeledPoint] = {
+    val arr = new Array[WeightedLabeledPoint](1000)
     for (i <- 0 until 1000) {
       if (i < 600) {
-        arr(i) = new LabeledPoint(1.0, Vectors.dense(0.0, 1.0))
+        arr(i) = new WeightedLabeledPoint(1.0, Vectors.dense(0.0, 1.0))
       } else {
         arr(i) = new WeightedLabeledPoint(0.0, Vectors.dense(1.0, 0.0))
       }