Scala Lists of lists of integers

Question

I am new to Scala and am a bit confused.

Given a list of lists List[List[Int]], how can one call a specific index of an element of each list, for example the second element of each list?

Answer 1

Simple:

val ints = List( List(1,2), List(3,4) )
val result = ints.map( l => l(1) )

This will produce (2,4).

Answer 2

While both of the other answers work, here is another version that is both safe to use and not complex. You can lift a Seq to a Function[Int, Option[A]] to make apply return Options instead of throwing exceptions. In Addition you can use flatMap instead of map{...}.flatten

List(List(1), List(1,2), List(1,2,3)).flatMap { xs =>
  xs.lift(1)
}

// res1: List[Int] = List(2, 2)