How do you rotate (circular shift) of a Scala collection

Question

I can do this quite easily, and cleanly, using a for loop. For instance, if I wanted to traverse a Seq from every element back to itself I would do the

Answer 1

Given:

val seq = Seq(1,2,3,4,5)

Solution:

seq.zipWithIndex.groupBy(_._2<3).values.flatMap(_.map(_._1))

or

seq.zipWithIndex.groupBy(_._2<3).values.flatten.map(_._1)

Result:

List(4, 5, 1, 2, 3)

1. If rotation is more than length of collection - we need to use rotation%length, if negative than formula (rotation+1)%length and take absolute value.
2. It's not efficient