Random Generator Projection Exploration

RandomGeneratorProjection.scala

import util.Random

object RandomGeneratorProjection {

  // in : size of the input generator
  // out : size of the output generator
  def d(in: Int, out: Int): Int = {
    assert(in > 1, "in must be greater than 1")
    assert(out > 0, "out must be greater than 0")

    List.fill(out)(Random.nextInt(in)).zipWithIndex.sorted.reverse match {
      case (a,_) :: (b,_) :: _ if a == b => d(in, out)
      case (_,i) :: _ => i
    }
  }

  def verify(in: Int, out: Int, trials: Int) =
    (0 until trials).map { i => d(in, out) }.groupBy { i => i }.map { case (k,v) => k -> v.size }

  // an approximate verification visual
  def printVerifyViz(i: Map[Int, Int]) {
    val z = i.head._2 / 80
    i.toList.sorted.foreach { case (k,v) => println(s"k: $k ${"."*(v/z)}") }
  }
}