def mean
      mean = Pair.new(0, 0)
      weight = 0

      objects.each do |object, n|
        (1..n).each do |_i|
          mean + object
          weight += 1
        end
      end
      mean / weight
      mean
    end
def mean
      mean = Pair.new(0, 0)
      weight = 0

      objects.each do |object, n|
        (1..n).each do |_i|
          mean + object
          weight += 1
        end
      end
      mean / weight
      mean
    end
Returns the weighted mean value of the cluster