Testing to see if the to_i(16)/modulo of SHA256 has a uniform distribution

sha.rb

h = {}
1_000_000.times do |i|
  puts i if (i % 1_000 == 0)
  str = (0...16).map { (65 + rand(26)).chr }.join
  digest = (Digest::SHA256.new << str).to_s
  num = digest.to_i(16) % 100
  h[num] ||= 0
  h[num] += 1
end

h.values.inject(0) {|s,n| s + n } / h.values.size.to_f #=> 10000.0

module Enumerable

  def sum
    return self.inject(0){|accum, i| accum + i }
  end

  def mean
    return self.sum / self.length.to_f
  end

  def sample_variance
    m = self.mean
    sum = self.inject(0){|accum, i| accum + (i - m) ** 2 }
    return sum / (self.length - 1).to_f
  end

  def standard_deviation
    return Math.sqrt(self.sample_variance)
  end

end

h.values.standard_deviation #=> 96.69550249117175