# File lib/core/facets/array/probability.rb, line 10
  def probability
    probs = Hash.new(0.0)
    size = 0.0
    each do |e|
      probs[e] += 1.0
      size += 1.0
    end
    probs.keys.each{ |e| probs[e] /= size }
    probs
  end