Scala: How to check if all items are unique in a Seq?

Question

Is there a more idiomatic and maybe faster way to check if there are duplicates in a Seq, than this:

mySeq.size == mySeq.toSet.size

Nope, other than writing your own implicits. See similar question here: http://stackoverflow.com/questions/7691971/easiest-way-to-decide-if-list-contains-duplicates — Akos Krivachy, May 20 '14 at 06:50

score 3 · Accepted Answer · answered May 20 '14 at 13:22

3

This will be faster, because it can terminate early:

def allUnique[A](to: TraversableOnce[A]) = {
  val set = scala.collection.mutable.Set[A]()
  to.forall { x =>
    if (set(x)) false else {
      set += x
      true
    }
  }
}

answered May 20 '14 at 13:22

wingedsubmariner

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Scala: How to check if all items are unique in a Seq?

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