graph/example/remove_edge_if_dir.cpp

#include <iostream>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/graph_utility.hpp>

/*
  Sample output:

  original graph:
  0 --> 3 2 3 
  1 --> 3 
  2 --> 0 
  3 --> 2 

  removing edges (0,3)
  0 --> 2 
  1 --> 3 
  2 --> 0 
  3 --> 2 
  removing edge (0,2) and (3, 2)
  0 --> 
  1 --> 3 
  2 --> 0 
  3 --> 
  
 */

using namespace boost;

typedef adjacency_list<vecS, vecS, directedS> Graph;

struct has_target {
  has_target(graph_traits<Graph>::vertex_descriptor v,
	     Graph& g_) : targ(v), g(g_) { }
  bool operator()(graph_traits<Graph>::edge_descriptor e) {
    return target(e, g) == targ;
  }
  graph_traits<Graph>::vertex_descriptor targ;
  Graph& g;
};

int
main()
{
  typedef std::pair<std::size_t,std::size_t> Edge;
  Edge edges[6] = { Edge(0,3), Edge(0,2), Edge(0, 3),
		    Edge(1,3),
		    Edge(2, 0),
		    Edge(3, 2) };

  Graph g(4, edges, edges + 6);

  std::cout << "original graph:" << std::endl;
  print_graph(g, get(vertex_index, g));
  std::cout << std::endl;

  std::cout << "removing edges (0,3)" << std::endl;
  remove_out_edge_if(vertex(0,g), has_target(vertex(3,g), g), g);
  print_graph(g, get(vertex_index, g));

  std::cout << "removing edge (0,2) and (3, 2)" << std::endl;
  remove_edge_if(has_target(vertex(2,g), g), g);
  print_graph(g, get(vertex_index, g));

  return 0;
}