[Boost-users] BGL: ColorMap for depth_first_search

From: Christian Sturz (linuxkaffee_at_[hidden])
Date: 2008-02-26 09:14:47

Hi,

I've an urgent question on a BGL algorithm.

I want to use the depth_first_search algorithm from the Boost
Graph Library. However, I've problems with the definition of
my own ColorMap. To illustrate this, here is an example
(taken from http://www.boost.org/libs/graph/example/dfs-example.cpp):

int
main()
{
  // Select the graph type we wish to use
  typedef adjacency_list < vecS, vecS, directedS > graph_t;
  typedef graph_traits < graph_t >::vertices_size_type size_type;

  // Set up the vertex names
  enum
  { u, v, w, x, y, z, N };
  char name[] = { 'u', 'v', 'w', 'x', 'y', 'z' };

  // Specify the edges in the graph
  typedef std::pair < int, int >E;
  E edge_array[] = { E(u, v), E(u, x), E(x, v), E(y, x),
    E(v, y), E(w, y), E(w, z), E(z, z) };

  graph_t g(edge_array, edge_array + sizeof(edge_array) / sizeof(E), N);

  // Typedefs
  typedef boost::graph_traits < graph_t >::vertex_descriptor Vertex;
  typedef size_type* Iiter;

  // discover time and finish time properties
  std::vector < size_type > dtime(num_vertices(g));
  std::vector < size_type > ftime(num_vertices(g));
  size_type t = 0;
  dfs_time_visitor < size_type * >vis(&dtime[0], &ftime[0], t);

  // Some arbitrary vertex as root (start point of DFS)
  Vertex root = source( edge_array[2],g );

  depth_first_search(g, visitor(vis), myColorMap, root );
 
  return 0;
}

My problem is the definition of "myColorMap" which must be 
a model of Read/Write Property Map. However, I have no idea
how to define a working ColorMap. It would be fully sufficient
to take the default color map which is used when DFS is invoked
with "depth_first_search(g, visitor(vis));"

Do you have an idea how I define a ColorMap that I can use
for "myColorMap"?

Any help is appreciated.

Thank you.
Christian
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