34 - Spark RDD Actions - fold() - Code Demo
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Chapter 06 - Spark RDD Actions - fold() - Code Demo
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Action: fold(zeroValue, func)
Since RDD’s are partitioned, the fold() function takes full advantage of it by first aggregating elements in each partition and then aggregating results of all partitions to get the final result. The result of this function is the same as this RDD type.
fold() takes the following arguments:
zeroValue – Initial value to be used for each partition in folding, this value would be used to initialize the accumulator for each partition. We mostly use 0 for integer and empty for collections.
func – a function used to both accumulate results within a partition and combine results from all partitions
Example:
final var sum = myRdd.fold(0D, Double::sum);
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