[Boost-users] vertex descriptors

From: Luis Quesada (luque_at_[hidden])
Date: 2005-11-30 14:06:03

Dear all,

Sorry for the newbie question!

Given the index of a vertex, how can I get its descriptor? I guess 
function vertex (page 225 of The Boost Graph Library) does  that but the 
function is not defined.

In fact, what I want to do is to  check whether an edge belongs to a 
graph in a context where descriptors get invalidated after vertex removals?

Suppose I have done this:

   // create a typedef for the Graph type
   typedef adjacency_list<vecS, vecS, bidirectionalS> Graph;

  // Make convenient labels for the vertices
  enum { A, B, C, D, E, N };
  const int num_vertices = N;
  const char* name = "ABCDE";

  // writing out the edges in the graph
  typedef std::pair<int, int> Edge;
  Edge edge_array[] =    { Edge(A,B), Edge(A,D), Edge(C,A), Edge(D,C),
    Edge(C,E), Edge(B,D), Edge(D,E) };
  const int num_edges = sizeof(edge_array)/sizeof(edge_array[0]);

  // declare a graph object
  Graph g(num_vertices);

Then I remove some vertices. Now I want to check whether edge <A,B> is 
still there. Calling edge(A,B,g) would not be OK because the descriptors 
are no longer referring to the same vertices....

Thanks in advance for your answer,

Luis