How to resolve the algorithm One of n lines in a file step by step in the Scala programming language

Published on 12 May 2024 09:40 PM
#Scala

How to resolve the algorithm One of n lines in a file step by step in the Scala programming language

Table of Contents

Problem Statement

A method of choosing a line randomly from a file: Is to:

Note: You may choose a smaller number of repetitions if necessary, but mention this up-front. Note: This is a specific version of a Reservoir Sampling algorithm: https://en.wikipedia.org/wiki/Reservoir_sampling

Let's start with the solution:

Step by Step solution about How to resolve the algorithm One of n lines in a file step by step in the Scala programming language

Source code in the scala programming language

def one_of_n(n: Int, i: Int = 1, j: Int = 1): Int =
  if (n < 1) i else one_of_n(n - 1, if (scala.util.Random.nextInt(j) == 0) n else i, j + 1)

def simulate(lines: Int, iterations: Int) = {
  val counts = new Array[Int](lines)
  for (_ <- 1 to iterations; i = one_of_n(lines) - 1) counts(i) = counts(i) + 1
  counts
}

println(simulate(10, 1000000) mkString "\n")

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