class NetworkX::MultiGraph

Describes the class for making MultiGraphs

@attr_reader adj [Hash{ Object => Hash{ Object => Hash{ Integer => Hash{ Object => Object } } } }]

Stores the edges and their attributes in an adjencency list form

@attr_reader nodes [Hash{ Object => Hash{ Object => Object } }] Stores the nodes and their attributes @attr_reader graph [Hash{ Object => Object }] Stores the attributes of the gra

Public Instance Methods

add_edge(node_1, node_2, **edge_attrs) click to toggle source

Adds the respective edge

@example Add an edge with attribute name

graph.add_edge(node1, node2, name: "Edge1")

@example Add an edge with no attribute

graph.add_edge("Bangalore", "Chennai")

@param node_1 [Object] the first node of the edge @param node_2 [Object] the second node of the edge @param edge_attrs [Hash{ Object => Object }] the hash of the edge attributes

# File lib/networkx/multigraph.rb, line 31
def add_edge(node_1, node_2, **edge_attrs)
  add_node(node_1)
  add_node(node_2)
  key = new_edge_key(node_1, node_2)
  all_edge_attrs = @adj[node_1][node_2] || {}
  all_edge_attrs[key] = edge_attrs
  @adj[node_1][node_2] = all_edge_attrs
  @adj[node_2][node_1] = all_edge_attrs
end
edge?(node_1, node_2, key=nil) click to toggle source

Checks if the the edge consisting of two nodes is present in the graph

@example

graph.edge?(node_1, node_2)

@param node_1 [Object] the first node of the edge to be checked @param node_2 [Object] the second node of the edge to be checked @param key [Integer] the key of the given edge

Calls superclass method NetworkX::Graph#edge?
# File lib/networkx/multigraph.rb, line 97
def edge?(node_1, node_2, key=nil)
  super(node_1, node_2) if key.nil?
  node?(node_1) && @adj[node_1].key?(node_2) && @adj[node_1][node_2].key?(key)
end
edge_subgraph(edges) click to toggle source

Returns subgraph conisting of given edges

@example

graph.edge_subgraph([%w[Nagpur Wardha], %w[Nagpur Mumbai]])

@param edges [Array<Object, Object>] the edges to be included in the subraph

# File lib/networkx/multigraph.rb, line 153
def edge_subgraph(edges)
  case edges
  when Array, Set
    sub_graph = NetworkX::MultiGraph.new(@graph)
    edges.each do |u, v|
      raise KeyError, "Edge between #{u} and #{v} does not exist in the graph!" unless @nodes.key?(u)\
                                                                                && @adj[u].key?(v)
      sub_graph.add_node(u, @nodes[u])
      sub_graph.add_node(v, @nodes[v])
      @adj[u][v].each { |_, keyval| sub_graph.add_edge(u, v, keyval) }
    end
    return sub_graph
  else
    raise ArgumentError, 'Expected Argument to be Array or Set of edges, '\
    "received #{edges.class.name} instead."
  end
end
new_edge_key(node_1, node_2) click to toggle source

Returns a new key

@param node_1 [Object] the first node of a given edge @param node_2 [Object] the second node of a given edge

# File lib/networkx/multigraph.rb, line 13
def new_edge_key(node_1, node_2)
  return 0 if @adj[node_1][node_2].nil?
  key = @adj[node_1][node_2].length
  key += 1 while @adj[node_1][node_2].key?(key)
  key
end
number_of_edges() click to toggle source

Returns number of edges

@example

graph.number_of_edges
# File lib/networkx/multigraph.rb, line 85
def number_of_edges
  @adj.values.flat_map(&:values).map(&:length).inject(:+) / 2
end
remove_edge(node_1, node_2, key=nil) click to toggle source

Removes edge from the graph

@example

graph.remove_edge('Noida', 'Bangalore')

@param node_1 [Object] the first node of the edge @param node_2 [Object] the second node of the edge

Calls superclass method NetworkX::Graph#remove_edge
# File lib/networkx/multigraph.rb, line 50
def remove_edge(node_1, node_2, key=nil)
  if key.nil?
    super(node_1, node_2)
    return
  end
  raise KeyError, "#{node_1} is not a valid node." unless @nodes.key?(node_1)
  raise KeyError, "#{node_2} is not a valid node" unless @nodes.key?(node_2)
  raise KeyError, 'The given edge is not a valid one.' unless @adj[node_1].key?(node_2)
  raise KeyError, 'The given edge is not a valid one.' unless @adj[node_1][node_2].key?(key)
  @adj[node_1][node_2].delete(key)
  @adj[node_2][node_1].delete(key)
end
size(is_weighted=false) click to toggle source

Returns the size of the graph

@example

graph.size(true)

@param is_weighted [Bool] if true, method returns sum of weights of all edges

else returns number of edges
# File lib/networkx/multigraph.rb, line 70
def size(is_weighted=false)
  if is_weighted
    graph_size = 0
    @adj.each do |_, hash_val|
      hash_val.each { |_, v| v.each { |_, attrs| graph_size += attrs[:weight] if attrs.key?(:weight) } }
    end
    return graph_size / 2
  end
  number_of_edges
end
subgraph(nodes) click to toggle source

Returns subgraph consisting of given array of nodes

@example

graph.subgraph(%w[Mumbai Nagpur])

@param nodes [Array<Object>] the nodes to be included in the subgraph

# File lib/networkx/multigraph.rb, line 127
def subgraph(nodes)
  case nodes
  when Array, Set
    sub_graph = NetworkX::MultiGraph.new(@graph)
    nodes.each do |u, _|
      raise KeyError, "#{u} does not exist in the current graph!" unless @nodes.key?(u)
      sub_graph.add_node(u, @nodes[u])
      @adj[u].each do |v, edge_val|
        edge_val.each { |_, keyval| sub_graph.add_edge(u, v, keyval) if @adj[u].key?(v) && nodes.include?(v) }
      end
      return sub_graph
    end
  else
    raise ArgumentError, 'Expected Argument to be Array or Set of nodes, '\
                         "received #{nodes.class.name} instead."
  end
end
to_undirected() click to toggle source

Returns the undirected version of the graph

@example

graph.to_undirected
# File lib/networkx/multigraph.rb, line 106
def to_undirected
  graph = NetworkX::Graph.new(@graph)
  @nodes.each { |node, node_attr| graph.add_node(node, node_attr) }
  @adj.each do |node_1, node_1_edges|
    node_1_edges.each do |node_2, node_1_node_2|
      edge_attrs = {}
      node_1_node_2.each { |_key, attrs| edge_attrs.merge!(attrs) }
      graph.add_edge(node_1, node_2, edge_attrs)
    end
  end
  graph
end