Array#repeated_sample implementation example for #ruby IRC

repeated_sample.rb

# frozen_string_literal: true

require 'securerandom'

module RepeatedSample
  refine Array do
    def repeated_sample(sample_size = 1)
      m = 1
      limit = size
      while limit * size <= 0x100000000
        limit *= size
        m += 1
      end

      result = []

      while m <= sample_size
        rs = SecureRandom.random_number(limit)
        is = rs.digits(size)
        (m - is.length).times { is << 0 }
        result.concat values_at(*is)
        sample_size -= m
      end

      if sample_size.positive?
        rs = SecureRandom.random_number(limit)
        is = rs.digits(size)
        if is.length < sample_size
          (sample_size - is.size).times { is << 0 }
        else
          is.pop while sample_size < is.length
        end
        result.concat values_at(*is)
      end

      result
    end
  end
end

using RepeatedSample

pp [*'a'..'z', *'A'..'Z', *'0'..'9'].repeated_sample(6)