Genetic algorithm

gistfile1.rb

class ProceduralFiveDigits
  def initialize
    @new_population = Array.new(100) { generate_individual }
    reset
  end

  def evolve
    1000.times do
      100.times do
        @parent_a, @parent_b = [pick_individual, pick_individual]
        @new_population.push cross_parents
      end
      reset
    end
    best_individual
  end

  private
  def generate_individual
    Array.new(5) { (0..9).to_a.sample }
  end

  def pick_individual
    fitness_left = @total_fitness
    @population.find {|i| fitness_left -= fitness(i); fitness_left <= 0 }
  end

  def cross_parents
    point = rand(5)
    @parent_a.first(point) + @parent_b.last(5-point)
  end

  def best_individual
    @population.first
  end

  def reset
    @population = @new_population.sort {|a,b| fitness(a) <=> fitness(b) }
    @new_population = []
    @total_fitness = @population.inject(0) {|s,i| s + fitness(i) }
  end

  def fitness(i)
    i.inject(:+)
  end
end