[SPARK-8704] [ML] [PySpark] Add missing methods in StandardScaler

Add std, mean to StandardScalerModel
getVectors, findSynonyms to Word2Vec Model
setFeatures and getFeatures to hashingTF

Author: MechCoder <manojkumarsivaraj334@gmail.com>

Closes #7086 from MechCoder/missing_model_methods and squashes the following commits:

9fbae90 [MechCoder] Add type
6e3d6b2 [MechCoder] [SPARK-8704] Add missing methods in StandardScaler (ML and PySpark)

mllib/src/main/scala/org/apache/spark/ml/feature/StandardScaler.scala

@@ -106,6 +106,12 @@ class StandardScalerModel private[ml] (
     scaler: feature.StandardScalerModel)
   extends Model[StandardScalerModel] with StandardScalerParams {
 
+  /** Standard deviation of the StandardScalerModel */
+  val std: Vector = scaler.std
+
+  /** Mean of the StandardScalerModel */
+  val mean: Vector = scaler.mean
+
   /** @group setParam */
   def setInputCol(value: String): this.type = set(inputCol, value)
 

python/pyspark/ml/feature.py

@@ -627,6 +627,10 @@ class StandardScaler(JavaEstimator, HasInputCol, HasOutputCol):
     >>> df = sqlContext.createDataFrame([(Vectors.dense([0.0]),), (Vectors.dense([2.0]),)], ["a"])
     >>> standardScaler = StandardScaler(inputCol="a", outputCol="scaled")
     >>> model = standardScaler.fit(df)
+    >>> model.mean
+    DenseVector([1.0])
+    >>> model.std
+    DenseVector([1.4142])
     >>> model.transform(df).collect()[1].scaled
     DenseVector([1.4142])
     """
@@ -692,6 +696,20 @@ class StandardScalerModel(JavaModel):
     Model fitted by StandardScaler.
     """
 
+    @property
+    def std(self):
+        """
+        Standard deviation of the StandardScalerModel.
+        """
+        return self._call_java("std")
+
+    @property
+    def mean(self):
+        """
+        Mean of the StandardScalerModel.
+        """
+        return self._call_java("mean")
+
 
 @inherit_doc
 class StringIndexer(JavaEstimator, HasInputCol, HasOutputCol):