# File lib/ai4r/clusterers/k_means.rb, line 88
      def calc_initial_centroids
        @centroids = []
        tried_indexes = []
        while @centroids.length < @number_of_clusters && 
            tried_indexes.length < @data_set.data_items.length
          random_index = rand(@data_set.data_items.length)
          if !tried_indexes.include?(random_index)
            tried_indexes << random_index
            if !@centroids.include? @data_set.data_items[random_index] 
              @centroids << @data_set.data_items[random_index] 
            end
          end
        end
        @number_of_clusters = @centroids.length
      end