CODEWITHSUNDEEP
scalaapache-sparkreduce
Jimit Raithatha
Jimit Raithatha

Reputation: 398

reduce function gives negative answer

Friends,

I'm trying to learn Scala coding and exploring the reduce() function as of now. I don't understand why the following piece of code to multiply all numbers in a list give me negative output:

    val inputRDD=sc.parallelize(List(1,2,3,3,4,5,6,7,8,9,19,22,21,25,34,56,4,32,56,70))

    val result=inputRDD.reduce((x,y)=>x*y)

    println(result)`

I get the answer "-1619001344" when i run the above code. If i try using "+" in reduce instead of "*" i get the proper sum, but not otherwise. I also tried converting result to Int, String and Long

Upvotes: 1

Views: 380

Answers (1)

marios
marios

Reputation: 8996

The Int and Long types are both overflowing, so you need to use BigInt for this operation. 

val inputRDD = sc.parallelize(List(1,2,3,3,4,5,6,7,8,9,19,22,21,25,34,56,4,32,56,70))

val inputRDDasBigInt = inputRDD.map(x => scala.BigInt(x))
val result = inputRDDasBigInt.reduce((x,y)=>x*y)

println(result)
228235320014929920000

Upvotes: 2

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