[Boost-users] [Graph] remove edges and reinsert them

From: Dominik Heide (dheide_at_[hidden])
Date: 2007-06-04 12:11:46

Hi there,

I want to delete a vertex from a graph and later reinsert it again. I did this 
by removing all edges from that vertex and later adding the edges again. But 
the behavior of the program quite strange.

First, I use a undirected adjacancy list 

typedef adjacency_list<vecS, vecS, undirectedS, no_property, no_property> 
Graph;

When, use 

Graph g, gs;

// set g

typename graph_traits<GraphT>::vertex_iterator vi, ve, vii, vei;
typename graph_traits<GraphT>::out_edge_iterator out_i, out_end, tmp;
for( tie(vi, ve) = vertices(g); vi != ve; vi++)
{
  gs = g;
  clear_vertex( *vi, g)

  // some code
  
  g = gs;
}

everything is fine. I don't want to save the whole graph since I only delete a 
couple of edges. Therefore, I did

vector<typename graph_traits<GraphT>::vertex_descriptor> deletedEdges;
typename vector<typename graph_traits<GraphT>::vertex_descriptor>::iterator 
dei;

typename graph_traits<GraphT>::vertex_iterator vi, ve, vii, vei;
typename graph_traits<GraphT>::out_edge_iterator out_i, out_end, tmp;

...

for( tie(vi, ve) = vertices(g); vi != ve; vi++)
{
  for( tie( out_i, out_end ) = out_edges( *vi, g); out_i != out_end; out_i++)
  {
    deletedEdges.push_back(target(*out_i, g));
  }
  clear_vertex( *vi, g)

  // some code
 
  for(dei = deletedEdges.begin(); dei < deletedEdges.end(); ++dei)
  {
    add_edge( *vi, *dei, g);
  }
}

This code does not restore the graph completely. Although it looks the same 
the shortest paths are different to the ones with the above code. 

Is there something about clear_vertex() I don't know and therefore don't 
restore corectly?

Any help appreachiated, Thank you, Dominik