CODEWITHSUNDEEP
scaladictionarymerge
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The Best

Reputation: 361

Merging maps in scala by key and sum or append the value

im looking for a way to merge maps. i can write code every time i need to merge maps by their keys but the problem is that the manipulation on the value is different all the time (for strings , lists of int)

is their a library for this issue ?

for example my input is : 

  //value is int - need to sum the values
  val example1 = Map("a" -> 1 , "b" -> 1 , "c" -> 7)
  val example2 = Map("a" -> 1 , "e" -> 5 , "f" -> 2)

  //value is list - need to append 
  val example1 = Map("a" -> List(1) , "b" -> List(3) , "c" -> List(2))
  val example2 = Map("a" -> List(4) , "e" -> List(1) , "f" -> List(1))

  //value is string - nned to append
  val example1 = Map("a" -> "asd" , "b" -> "efd" , "c" ->  "sdf")
  val example2 = Map("a" -> "ads" , "e" -> "sdfds" , "f" -> "czxc2")

Upvotes: 0

Views: 339

Answers (1)

Nimrod007
Nimrod007

Reputation: 9913

I wrote a blog post about this , check it out :

http://www.nimrodstech.com/scala-map-merge/

basically using scalaz semi group you can achieve this pretty easily

would look something like :

  import scalaz.Scalaz._
  example1 |+| example2

Upvotes: 6

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