Scala - How to convert from List of tuples of type (A,B) to type (B,A) using map

Question

What is the best way to convert a List[String, Int] A to List[Int, String] B. I wanted to use the map function which would iterate through all items in my list A and then return a new list B however whenever I apply the map function on the list A it complains about wrong number of arguments

val listA:List[(String, Int)] = List(("graduates", 20), ("teachers", 10), ("students", 300))
val listB:List[(Int, String)] = listA.map((x:String, y:Int) => y, x)

Any suggestions? Thanks

Answer 1

How about this:

val listB = listA.map(_.swap)

Answer 2

You need to use pattern matching to get the elements of a pair. I swear a question like this was asked just a few days ago....

listA.map{case (a,b) => (b,a)}