How to resolve the algorithm Cumulative standard deviation step by step in the Scala programming language

Published on 12 May 2024 09:40 PM
#Scala

How to resolve the algorithm Cumulative standard deviation step by step in the Scala programming language

Table of Contents

Problem Statement

Write a stateful function, class, generator or co-routine that takes a series of floating point numbers, one at a time, and returns the running standard deviation of the series. The task implementation should use the most natural programming style of those listed for the function in the implementation language; the task must state which is being used. Do not apply Bessel's correction; the returned standard deviation should always be computed as if the sample seen so far is the entire population.

Use this to compute the standard deviation of this demonstration set,

{ 2 , 4 , 4 , 4 , 5 , 5 , 7 , 9 }

{\displaystyle {2,4,4,4,5,5,7,9}}

, which is

2

{\displaystyle 2}

.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Cumulative standard deviation step by step in the Scala programming language

Source code in the scala programming language

import scala.math.sqrt

object StddevCalc extends App {

  def calcAvgAndStddev[T](ts: Iterable[T])(implicit num: Fractional[T]): (T, Double) = {
    def avg(ts: Iterable[T])(implicit num: Fractional[T]): T =
      num.div(ts.sum, num.fromInt(ts.size)) // Leaving with type of function T

    val mean: T = avg(ts) // Leave val type of T
    // Root of mean diffs
    val stdDev = sqrt(ts.map { x =>
      val diff = num.toDouble(num.minus(x, mean))
      diff * diff
    }.sum / ts.size)

    (mean, stdDev)
  }

  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))))

  println(s"Successfully completed without errors. [total ${scala.compat.Platform.currentTime - executionStart}ms]")

}

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