PySpark groupByKey returning pyspark.resultiterable.ResultIterable

Question

I am trying to figure out why my groupByKey is returning the following:

[(0, ), (1, 

        

Answer 1

Example:

r1 = sc.parallelize([('a',1),('b',2)])
r2 = sc.parallelize([('b',1),('d',2)])
r1.cogroup(r2).mapValues(lambda x:tuple(reduce(add,__builtin__.map(list,x))))

Result:

[('d', (2,)), ('b', (2, 1)), ('a', (1,))]