[SPARK-6660][MLLIB] pythonToJava doesn't recognize object arrays

davies

Author: Xiangrui Meng <meng@databricks.com>

Closes #5318 from mengxr/SPARK-6660 and squashes the following commits:

0f66ec2 [Xiangrui Meng] recognize object arrays
ad8c42f [Xiangrui Meng] add a test for SPARK-6660

mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala

@@ -1113,7 +1113,10 @@ private[spark] object SerDe extends Serializable {
       iter.flatMap { row =>
         val obj = unpickle.loads(row)
         if (batched) {
-          obj.asInstanceOf[JArrayList[_]].asScala
+          obj match {
+            case list: JArrayList[_] => list.asScala
+            case arr: Array[_] => arr
+          }
         } else {
           Seq(obj)
         }

python/pyspark/mllib/tests.py

@@ -36,6 +36,7 @@ if sys.version_info[:2] <= (2, 6):
 else:
     import unittest
 
+from pyspark.mllib.common import _to_java_object_rdd
 from pyspark.mllib.linalg import Vector, SparseVector, DenseVector, VectorUDT, _convert_to_vector,\
     DenseMatrix, Vectors, Matrices
 from pyspark.mllib.regression import LabeledPoint
@@ -641,6 +642,13 @@ class FeatureTest(PySparkTestCase):
         idf = model.idf()
         self.assertEqual(len(idf), 11)
 
+
+class SerDeTest(PySparkTestCase):
+    def test_to_java_object_rdd(self):  # SPARK-6660
+        data = RandomRDDs.uniformRDD(self.sc, 10, 5, seed=0L)
+        self.assertEqual(_to_java_object_rdd(data).count(), 10)
+
+
 if __name__ == "__main__":
     if not _have_scipy:
         print "NOTE: Skipping SciPy tests as it does not seem to be installed"