CODEWITHSUNDEEP
scala
Rajeev
Rajeev

Reputation: 5012

Erring output with Scala map

Getting unexpected output from map iteration of group result.

val res = List(3,3,5,7,7).groupBy(x => x)
//o/p res: scala.collection.immutable.Map[Int,List[Int]] = Map(5 -> List(5), 7 -> List(7, 7), 3 -> List(3, 3))

val res1 = List(3,3,5,7,7).groupBy(x => x).map(x => (x._2.size, x._1))
//error o:p  => res1: scala.collection.immutable.Map[Int,Int] = Map(1 -> 5, 2 -> 3)

second function is returning partial result. Why it failed process number 7 ?

Upvotes: 0

Views: 48

Answers (1)

Ende Neu
Ende Neu

Reputation: 15783

This happens because you are using as key the size of the list and both 7 and 3 have the same length so the latter overwrites the former, with different sizes:

scala> val res1 = List(3,3,5,7,7).groupBy(x => x).map(x => (x._2.size, x._1))
res0: scala.collection.immutable.Map[Int,Int] = Map(1 -> 5, 2 -> 3)

scala> val res1 = List(3,3,5,7,7, 7).groupBy(x => x).map(x => (x._2.size, x._1))
res1: scala.collection.immutable.Map[Int,Int] = Map(1 -> 5, 3 -> 7, 2 -> 3)

Upvotes: 4

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