Fisher-Yates shuffle algorithm with Ruby

#ruby #algorithms #shuffle

The simplest shuffle algorithm, Fisher-Yates, is widely used and easy to implement. I personally used it to create a card game in Sinatra:

# Fisher-Yates Shuffle Algorithm

module FisherYates

  def self.shuffle(numbers)
    n = numbers.length
    while n > 0 
      x = rand(n-=1)
      numbers[x], numbers[n] = numbers[n], numbers[x]
    end
    return numbers
  end

end

So let's imagine you want to use it in your Rails app, you could do something like this:

  def initialize(numbers)
    shuffle = FisherYates.shuffle(numbers)
    return shuffle.inspect
  end

If you want to test this script from shell, add this after FisherYates, and save as shuffle.rb. Add numbers as arguments, or just execute script to shuffle defined numbers from array:

  @numbers = [1,2,3,4,5,6,7,8,9,10,12,13,14]

  if ARGV.empty?
    puts FisherYates.shuffle(@numbers).inspect
  else
    puts FisherYates.shuffle(ARGV).inspect
  end