Find and replace an item in a Scala collection

Question

Let's say I have a list:

val list = List(1,2,3,4,5) 

I want to replace all / first elements that satisfy the predicate, I know the following way to do this: (for example, replace any number that even with -1)

 val filteredList = list.zipWithIndex.filter(_._2 % 2 == 0) val onlyFirst = list.updated(filteredList.head._2, -1) val all = for(i <- list) yield if(i % 2 ==0) -1 else i 

Is there any collection feature or a good Scala way that helps in this situation and has good performance ?

I also want to keep order, so I don't want to use filterNot and add other elements to the list like: (it is also inefficient)

 val onlyFirst = list.filterNot(_ % 2 != 0) ::: list.filter(_ % 2 == 0).map(x => -1) 

Answer 1

Simple and efficient: Replace all items

 list.map( x => if (x % 2 == 0) -1 else x ) 

Replace one item

 val index = list.indexWhere( _ % 2 == 0 ) list.updated(index, -1)