Example Node Maps

The following program shows how a node_map can be used. First a graph G with three nodes is defined. Then a node_map A of type int is created. The default value for A is 1. We output the values of A for the three nodes of G. Afterwards we assign new values to the nodes and output the result. Finally, we create a new node of G and make A valid for the all nodes of G. All nodes are assigned the default value 1.

#include <LEDA/graph/graph.h>
#include <LEDA/graph/node_map.h>

using namespace leda;

int main()
{
  graph G;
  node v1=G.new_node();
  node v2=G.new_node();
  node v3=G.new_node();
  
  node_map<int> A(G,1);  //define node map A for G
                            //and assign 1 to every node
  std::cout << A[v1] << " " << A[v2] << " " << A[v3] << std::endl;

  int i=0;node v;
  forall_nodes(v,G) {
    A[v]=i++; //assign new values
  }
  std::cout << A[v1] << " " << A[v2] << " " << A[v3] << std::endl;

  //if new nodes are generated for G, we need to make A
  //valid for the new nodes
  node v4=G.new_node();
  A.init(G);
  std::cout << A[v1] << " " << A[v2] << " " << A[v3] << " " << A[v4] << std::endl;
  //outputs "1 1 1 1"
 
  return 0;
}  

See also:

Node Maps

Associate Information with Graphs

Manual Entries:

Manual Page Node Maps

User Defined Parameter Types