# File lib/ai4r/clusterers/single_linkage.rb, line 47
      def build(data_set, number_of_clusters)
        @data_set = data_set
        @number_of_clusters = number_of_clusters
        
        @index_clusters = create_initial_index_clusters
        create_distance_matrix(data_set)
        while @index_clusters.length > @number_of_clusters
          ci, cj = get_closest_clusters(@index_clusters)
          update_distance_matrix(ci, cj)
          merge_clusters(ci, cj, @index_clusters)
        end
        @clusters = build_clusters_from_index_clusters @index_clusters
        
        return self
      end