Adding mean and variance to Scala collections.

TraversableWithStatistics.scala

package com.liveperson.predictivedialer.common.utils

/**
 * Created with IntelliJ IDEA.
 * User: mishaelr
 * Date: 1/16/14
 * Time: 3:12 PM
 */
object TraversableWithStatistics {
  implicit class RichTraversable[+A](collection: Traversable[A]){

    private def pow2[C, B >: C](x: C)(implicit num: Numeric[B]) = math.pow(num.toDouble(x), 2)

    def mean[B >: A](implicit num: Numeric[B]) = {
      num.toDouble(collection.sum[B]) / collection.size
    }

    def variance[B >: A](implicit num: Numeric[B]) = {
      collection.map(pow2[A, B]).mean - pow2(mean[B])
    }
  }
}

object Example extends App {
  import TraversableWithStatistics._
  println((1 to 100).variance)
}