What is reduce action in Spark

+1 vote

Can anyone explain how reduce() function works in Spark?

Jul 2, 2019 in Apache Spark by amrita

recategorized Jul 4, 2019 by Gitika 4,042 views

1 answer to this question.

+1 vote

Hey,

It takes a function that operates on two elements of the type in your RDD and returns a new element of the same type. A simple example of such a function is +, which we can use to sum our RDD.

 With reduce(), we can easily sum the elements of our RDD, count the number of elements, and perform other types of aggregations.

answered Jul 2, 2019 by Gitika
• 65,890 points
Can you explain in brief like, for the following example of code

rdd = sc.parallelize([1,2,3,4])

rdd.reduce(lambda a, b: a + b)

Can you explain in which way reduce performs sum operation according to below options.

option 1 - (1+2)+3)+4

option 2 - (1+2)+(3+4)
It happens as option 1

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