# File lib/ai4r/neural_network/hopfield.rb, line 128
      def initialize_weights(data_set)
        @weights = Array.new(@nodes.length-1) {|l| Array.new(l+1)}
        @nodes.each_index do |i|
          i.times do |j|
            @weights[i-1][j] = data_set.data_items.inject(0) { |sum, item| sum+= item[i]*item[j] }
          end
        end
      end