graph/example/filtered_graph.cpp

//=======================================================================
// Copyright 2001 University of Notre Dame.
// Author: Jeremy G. Siek
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================

/* 
   Sample output:

   filtered edge set: (A,B) (C,D) (D,B) 
   filtered out-edges:
   A --> B 
   B --> 
   C --> D 
   D --> B 
   E --> 
 */

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

template <typename EdgeWeightMap>
struct positive_edge_weight {
  positive_edge_weight() { }
  positive_edge_weight(EdgeWeightMap weight) : m_weight(weight) { }
  template <typename Edge>
  bool operator()(const Edge& e) const {
    return 0 < boost::get(m_weight, e);
  }
  EdgeWeightMap m_weight;
};


int main()
{
  using namespace boost;
  
  typedef adjacency_list<vecS, vecS, directedS,
    no_property, property<edge_weight_t, int> > Graph;
  typedef property_map<Graph, edge_weight_t>::type EdgeWeightMap;

  enum { A, B, C, D, E, N };
  const char* name = "ABCDE";
  Graph g(N);
  add_edge(A, B, 2, g);
  add_edge(A, C, 0, g);
  add_edge(C, D, 1, g);
  add_edge(C, E, 0, g);
  add_edge(D, B, 3, g);
  add_edge(E, C, 0, g);
  
  positive_edge_weight<EdgeWeightMap> filter(get(edge_weight, g));
  filtered_graph<Graph, positive_edge_weight<EdgeWeightMap> >
    fg(g, filter);

  std::cout << "filtered edge set: ";
  print_edges(fg, name);

  std::cout << "filtered out-edges:" << std::endl;
  print_graph(fg, name);
  
  return 0;
}