module-calculator.rb

module ExtraArrayMethods
  def average(*nums)
    nums.dup.inject(:+) / nums.length
  end

  def median(*nums)
    nums = nums.uniq.sort

    if nums.length < 4
      return nums[0] if nums.length == 1
      if nums.length == 2
        med = nums.dup.inject(:+).to_f / nums.length
        if med == med.round
          return med.round
        else return med
        end
      end
      return nums[1]
    end

    median(*nums[1..-2])
  end

  def mode(*nums)
    frequencies = Hash.new(0)
    nums.sort.each{|num| frequencies[num] += 1}
    modes = frequencies.select{|k, v| v == frequencies.values.max}
    modes.keys.length == 1 ? modes.keys[0] : modes.keys
  end
end