[SPARK-7105] [PYSPARK] [MLLIB] Support model save/load in GMM

This PR introduces save / load for GMM's in python API.

Also I refactored `GaussianMixtureModel` and inherited it from `JavaModelWrapper` with model being `GaussianMixtureModelWrapper`, a wrapper which provides convenience methods to `GaussianMixtureModel` (due to serialization and deserialization issues) and I moved the creation of gaussians to the scala backend.

Author: MechCoder <manojkumarsivaraj334@gmail.com>

Closes #7617 from MechCoder/python_gmm_save_load and squashes the following commits:

9c305aa [MechCoder] [SPARK-7105] [PySpark] [MLlib] Support model save/load in GMM

1 files changed, 6 insertions, 0 deletions

diff --git a/python/pyspark/mllib/util.py b/python/pyspark/mllib/util.py
index 875d3b2d64..916de2d6fc 100644
--- a/python/pyspark/mllib/util.py
+++ b/python/pyspark/mllib/util.py
@@ -21,7 +21,9 @@ import warnings
 
 if sys.version > '3':
     xrange = range
+    basestring = str
 
+from pyspark import SparkContext
 from pyspark.mllib.common import callMLlibFunc, inherit_doc
 from pyspark.mllib.linalg import Vectors, SparseVector, _convert_to_vector
 
@@ -223,6 +225,10 @@ class JavaSaveable(Saveable):
     """
 
     def save(self, sc, path):
+        if not isinstance(sc, SparkContext):
+            raise TypeError("sc should be a SparkContext, got type %s" % type(sc))
+        if not isinstance(path, basestring):
+            raise TypeError("path should be a basestring, got type %s" % type(path))
         self._java_model.save(sc._jsc.sc(), path)