Merge the values for each key using an associative and commutative reduce function. code example

Example: Merge the values for each key using an associative and commutative reduce function.

from operator import add
rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
sorted(rdd.reduceByKey(add).collect())
# [('a', 2), ('b', 1)]