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// Copyright (C) 2004-2008 The Trustees of Indiana University.
// Use, modification and distribution is subject to 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)
// Authors: Douglas Gregor
// Andrew Lumsdaine
// Example usage of breadth_first_search algorithm
// Enable PBGL interfaces to BGL algorithms
#include <boost/graph/use_mpi.hpp>
// Communicate via MPI
#include <boost/graph/distributed/mpi_process_group.hpp>
// Breadth-first search algorithm
#include <boost/graph/breadth_first_search.hpp>
// Distributed adjacency list
#include <boost/graph/distributed/adjacency_list.hpp>
// METIS Input
#include <boost/graph/metis.hpp>
// Graphviz Output
#include <boost/graph/distributed/graphviz.hpp>
// For choose_min_reducer
#include <boost/graph/distributed/distributed_graph_utility.hpp>
// Standard Library includes
#include <fstream>
#include <string>
#ifdef BOOST_NO_EXCEPTIONS
void
boost::throw_exception(std::exception const& ex)
{
std::cout << ex.what() << std::endl;
abort();
}
#endif
using namespace boost;
using boost::graph::distributed::mpi_process_group;
/* An undirected graph with distance values stored on the vertices. */
typedef adjacency_list<vecS, distributedS<mpi_process_group, vecS>, undirectedS,
/*Vertex properties=*/property<vertex_distance_t, std::size_t> >
Graph;
int main(int argc, char* argv[])
{
boost::mpi::environment env(argc,argv);
// Parse command-line options
const char* filename = "weighted_graph.gr";
if (argc > 1) filename = argv[1];
// Open the METIS input file
std::ifstream in(filename);
graph::metis_reader reader(in);
// Load the graph using the default distribution
Graph g(reader.begin(), reader.end(),
reader.num_vertices());
// Get vertex 0 in the graph
graph_traits<Graph>::vertex_descriptor start = vertex(0, g);
// Compute BFS levels from vertex 0
property_map<Graph, vertex_distance_t>::type distance =
get(vertex_distance, g);
// Initialize distances to infinity and set reduction operation to 'min'
BGL_FORALL_VERTICES(v, g, Graph) {
put(distance, v, (std::numeric_limits<std::size_t>::max)());
}
distance.set_reduce(boost::graph::distributed::choose_min_reducer<std::size_t>());
put(distance, start, 0);
breadth_first_search
(g, start,
visitor(make_bfs_visitor(record_distances(distance, on_tree_edge()))));
// Output a Graphviz DOT file
std::string outfile;
if (argc > 2)
outfile = argv[2];
else {
outfile = filename;
size_t i = outfile.rfind('.');
if (i != std::string::npos)
outfile.erase(outfile.begin() + i, outfile.end());
outfile += "-bfs.dot";
}
if (process_id(process_group(g)) == 0) {
std::cout << "Writing GraphViz output to " << outfile << "... ";
std::cout.flush();
}
write_graphviz(outfile, g,
make_label_writer(distance));
if (process_id(process_group(g)) == 0)
std::cout << "Done." << std::endl;
return 0;
}
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