Reduce a key-value pair into a key-list pair with Apache Spark

Question

I am writing a Spark application and want to combine a set of Key-Value pairs (K, V1), (K, V2), ..., (K, Vn) into one Key-Multivalue pair (K, [V1, V2, ...

Answer 1

I'm kind of late to the conversation, but here's my suggestion:

>>> foo = sc.parallelize([(1, ('a','b')), (2, ('c','d')), (1, ('x','y'))])
>>> foo.map(lambda (x,y): (x, [y])).reduceByKey(lambda p,q: p+q).collect()
[(1, [('a', 'b'), ('x', 'y')]), (2, [('c', 'd')])]