Fisher-Yates shuffle

gistfile1.scala

// Randomly permutate an array - Fisher-Yates shuffle (see: http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle)
// This method can also take a custom swap method, which is useful for example for Latin hypercube sampling
def shuffle[@specialized(Double) T](array: Array[T], swap: (T, T) => (T, T) = { (a: T, b: T) => (b, a) }): Array[T] = {
  val random = new scala.util.Random

  for (n <- array.length - 1 to 0 by -1) {
    val k = random.nextInt(n + 1)
    val (a, b) = swap(array(k), array(n)); array(k) = a; array(n) = b
  }

  array
}