Cumulative standard deviation: Difference between revisions

=={{header|Scala}}==

[[Category:Scala Implementations]]

{{libheader|Scala}}

<lang Scala>import scala.math._

import Numeric.Implicits._

object StddevCalc extends App {

def avg[T](ts: Iterable[T])(implicit num: Fractional[T]): T = {

num.div(ts.sum, num.fromInt(ts.size)) // Leaving with type of function T

}

def calcAvgAndStddev[T](ts: Iterable[T])(implicit num: Fractional[T]): (T, Double) = {

val mean = avg(ts) // Leave val type of T

val stdDev = // Root of mean diffs

sqrt(num.toDouble(ts.foldLeft(num.zero)((b, a) => num.plus(b, num.times(num.minus(a, mean), num.minus(a, mean))))) / ts.size)

(mean, stdDev)

}

def calcAvgAndStddev(ts: Iterable[BigDecimal]): (Double, Double) = // Overloaded for BigDecimal

calcAvgAndStddev(ts.map(_.toDouble))

println(calcAvgAndStddev(List(2.0E0, 4.0, 4, 4, 5, 5, 7, 9)))

println(calcAvgAndStddev(Set(1.0, 2, 3, 4)))

println(calcAvgAndStddev(0.1 to 1.1 by 0.05))

println(calcAvgAndStddev(List(BigDecimal(120), BigDecimal(1200))))

}</lang>