[SPARK-11531][ML] SparseVector error Msg

PySpark SparseVector should have "Found duplicate indices" error message

Author: Joshi <rekhajoshm@gmail.com>
Author: Rekha Joshi <rekhajoshm@gmail.com>

Closes #9525 from rekhajoshm/SPARK-11531.

python/pyspark/mllib/linalg/__init__.py

@@ -528,7 +528,9 @@ class SparseVector(Vector):
             assert len(self.indices) == len(self.values), "index and value arrays not same length"
             for i in xrange(len(self.indices) - 1):
                 if self.indices[i] >= self.indices[i + 1]:
-                    raise TypeError("indices array must be sorted")
+                    raise TypeError(
+                        "Indices %s and %s are not strictly increasing"
+                        % (self.indices[i], self.indices[i + 1]))
 
     def numNonzeros(self):
         """