added logic to handle leaf nodes

Signed-off-by: Manish Amde <manish9ue@gmail.com>

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

@@ -135,6 +135,11 @@ object DecisionTree extends Serializable {
     */
     def isSampleValid(parentFilters: List[Filter], labeledPoint: LabeledPoint): Boolean = {
 
+      //Leaf
+      if (parentFilters.length == 0 ){
+        return false
+      }
+
       for (filter <- parentFilters) {
         val features = labeledPoint.features
         val featureIndex = filter.split.feature

mllib/src/main/scala/org/apache/spark/mllib/tree/model/InformationGainStats.scala

@@ -0,0 +1,32 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.mllib.tree.model
+
+class InformationGainStats(val gain : Double,
+                           val impurity: Double,
+                           val leftImpurity : Double,
+                           val leftSamples : Long,
+                           val rightImpurity : Double,
+                           val rightSamples : Long) {
+
+  override def toString =
+    "gain = " + gain + ", impurity = " + impurity + ", left impurity = "
+    + leftImpurity + ", leftSamples = " + leftSamples + ", right impurity = "
+    + rightImpurity + ", rightSamples = " + rightSamples
+
+
+}