michaelmior / NoSE

module NoSE

  module Random

    # Generates a random graph using the Barbasi-Albert model

    class BarbasiAlbertNetwork < Network

      private

      # Create all the entities in the graph and their connections

      # @return [void]

        # Add the initial one or two entities

        @entities = [create_entity(0)]

        return if @nodes_nb == 1

        @entities << create_entity(1)

        add_link 0, 1

        return if @nodes_nb == 2

        @entities << create_entity(2)

        add_link 2, 0

        add_link 2, 1

        return if @nodes_nb == 3

        # Add and connect more entities as needed

        3.upto(@nodes_nb - 1).each do |node|

          @entities << create_entity(node)

          pick = Pickup.new(0.upto(node - 1).to_a,

                            key_func: ->(n) { n },

                            weight_func: ->(n) { @neighbours[n].size },

                            uniq: true)

          pick.pick(2).each do |node2|

            add_link node, node2

          end

        end

      end

    end

  end

end