Question

For a Scala List[Int] I can call the method max to find the maximum element value.

How can I find the index of the maximum element?

This is what I am doing now:

val max = list.max 
val index = list.indexOf(max)

Answer 1

One way to do this is to zip the list with its indices, find the resulting pair with the largest first element, and return the second element of that pair:

scala> List(0, 43, 1, 34, 10).zipWithIndex.maxBy(_._1)._2
res0: Int = 1

This isn’t the most efficient way to solve the problem, but it’s idiomatic and clear.