How can I find the index of the maximum value in a List in Scala?

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.

Answer 2

Since Seq is a function in Scala, the following code works:

list.indices.maxBy(list) 

Answer 3

even easier to read would be:

   val g = List(0, 43, 1, 34, 10)
   val g_index=g.indexOf(g.max)