[SPARK-8711] [ML] Add additional methods to PySpark ML tree models

Add numNodes and depth to treeModels, add treeWeights to ensemble Models.
Add __repr__ to all models.

Author: MechCoder <manojkumarsivaraj334@gmail.com>

Closes #7095 from MechCoder/missing_methods_tree and squashes the following commits:

23b08be [MechCoder] private [spark]
38a0860 [MechCoder] rename pyTreeWeights to javaTreeWeights
6d16ad8 [MechCoder] Fix Python 3 Error
47d7023 [MechCoder] Use np.allclose and treeEnsembleModel -> TreeEnsembleMethods
819098c [MechCoder] [SPARK-8711] [ML] Add additional methods ot PySpark ML tree models

1 files changed, 5 insertions, 0 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/ml/tree/treeModels.scala b/mllib/src/main/scala/org/apache/spark/ml/tree/treeModels.scala
index 1929f9d021..22873909c3 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/tree/treeModels.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/tree/treeModels.scala
@@ -17,6 +17,7 @@
 
 package org.apache.spark.ml.tree
 
+import org.apache.spark.mllib.linalg.{Vectors, Vector}
 
 /**
  * Abstraction for Decision Tree models.
@@ -70,6 +71,10 @@ private[ml] trait TreeEnsembleModel {
   /** Weights for each tree, zippable with [[trees]] */
   def treeWeights: Array[Double]
 
+  /** Weights used by the python wrappers. */
+  // Note: An array cannot be returned directly due to serialization problems.
+  private[spark] def javaTreeWeights: Vector = Vectors.dense(treeWeights)
+
   /** Summary of the model */
   override def toString: String = {
     // Implementing classes should generally override this method to be more descriptive.