How to split a sequence into two pieces by predicate?

Question

How do I split a sequence into two lists by a predicate?

Alternative: I can use filter and filterNot, or write my own method, but isn\'t th

Answer 1

I know I might be late for the party and there are more specific answers, but you could make good use of groupBy

val ret = List(1,2,3,4).groupBy(x => x % 2 == 0)

ret: scala.collection.immutable.Map[Boolean,List[Int]] = Map(false -> List(1, 3), true -> List(2, 4))

ret(true)
res3: List[Int] = List(2, 4)

ret(false)
res4: List[Int] = List(1, 3)

This makes your code a bit more future-proof if you need to change the condition into something non boolean.