gentest.rb

class Gene

end

class Person

  @genes = []

  CHROM_PAIRS = 23

  def initialize(genes=nil)
    @genes = []
    if !genes
      CHROM_PAIRS.times do 
        @genes << [Gene.new, Gene.new]
      end
    else
      @genes = genes
    end
  end


  def zygote
    zyg = []
    @genes.each do |gene_pair|
      zyg << gene_pair[rand(2)]
    end
    zyg
  end

  def recombine(zyg1, zyg2)
    genes = []
    CHROM_PAIRS.times do |i|
      genes << [zyg1[i], zyg2[i]]
    end
    genes
  end

  def mate(person)
    my_zyg = zygote
    their_zyg = person.zygote
    baby = recombine(my_zyg, their_zyg)
    Person.new(baby)
  end

  attr_accessor :genes

  def similarity(person)
    similar_count = 0
    @genes.flatten.each do |gene|
      similar_count += 1 if person.genes.flatten.include?(gene)
    end
    similar_count.to_f / @genes.flatten.size
  end
end


def simulate(example,
             &block)

  prob = 0
  1000.times do 
    prob += yield
  end

  puts "#{example}: #{prob.to_f / 1000.to_f}"
end

simulate("double cousins") do 
  p1 = Person.new
  p2 = Person.new
  p3 = Person.new
  p4 = Person.new

  c1 = p1.mate(p2)
  c2 = p1.mate(p2)
  c3 = p3.mate(p4)
  c4 = p3.mate(p4)
  g3_c1 = c1.mate(c3)
  g3_c2 = c2.mate(c4)
  g3_c1.similarity(g3_c2)
end

simulate("regular cousins") do 
  p1 = Person.new
  p2 = Person.new
  p3 = Person.new
  p4 = Person.new

  c1 = p1.mate(p2)
  c2 = p1.mate(p2)
  c3 = c1.mate(p3)
  c4 = c2.mate(p4)
  c3.similarity(c4)
end