QList<unsigned> ShortestPathComputer::getShortestPathVertices(const unsigned startVertexIndex, const unsigned endVertexIndex, float *pathLength/* = NULL*/)
{
QList<unsigned> shortestPathVertices;
VertexDescriptor startVertex = vertex(startVertexIndex, mGraph);
std::vector<VertexDescriptor> predecessorMap(num_vertices(mGraph));
std::vector<float> distanceMap(num_vertices(mGraph));
dijkstra_shortest_paths(mGraph, startVertex,
predecessor_map(boost::make_iterator_property_map(predecessorMap.begin(), get(boost::vertex_index, mGraph))).
distance_map(boost::make_iterator_property_map(distanceMap.begin(), get(boost::vertex_index, mGraph))));
if (pathLength)
{
*pathLength = distanceMap.at(endVertexIndex);
}
unsigned vertexIndex1 = endVertexIndex;
unsigned vertexIndex2 = predecessorMap.at(vertexIndex1);
while (vertexIndex2 != vertexIndex1)
{
shortestPathVertices.push_front(vertexIndex2);
vertexIndex1 = vertexIndex2;
vertexIndex2 = predecessorMap.at(vertexIndex1);
}
shortestPathVertices.pop_front(); //去掉起点
return shortestPathVertices;
}
int main(int, char *[])
{
typedef float Weight;
typedef boost::property<boost::edge_weight_t, Weight> WeightProperty;
typedef boost::property<boost::vertex_name_t, std::string> NameProperty;
typedef boost::adjacency_list < boost::listS, boost::vecS, boost::directedS,
NameProperty, WeightProperty > Graph;
typedef boost::graph_traits < Graph >::vertex_descriptor Vertex;
typedef boost::property_map < Graph, boost::vertex_index_t >::type IndexMap;
typedef boost::property_map < Graph, boost::vertex_name_t >::type NameMap;
typedef boost::iterator_property_map < Vertex*, IndexMap, Vertex, Vertex& > PredecessorMap;
typedef boost::iterator_property_map < Weight*, IndexMap, Weight, Weight& > DistanceMap;
// Create a graph
Graph g;
// Add named vertices
Vertex v0 = add_vertex(std::string("v0"), g);
Vertex v1 = add_vertex(std::string("v1"), g);
Vertex v2 = add_vertex(std::string("v2"), g);
Vertex v3 = add_vertex(std::string("v3"), g);
// Add weighted edges
Weight weight0 = 5;
Weight weight1 = 3;
Weight weight2 = 2;
Weight weight3 = 4;
add_edge(v0, v1, weight0, g);
add_edge(v1, v3, weight1, g);
add_edge(v0, v2, weight2, g);
add_edge(v2, v3, weight3, g);
// At this point the graph is
/* v0
.
/ \ 2
/ \
/ . v2
5/ \
/ \ 4
/ \
v1----------- v3
3
*/
// Create things for Dijkstra
std::vector<Vertex> predecessors(num_vertices(g)); // To store parents
std::vector<Weight> distances(num_vertices(g)); // To store distances
/* works
//////////////
IndexMap indexMap = get(boost::vertex_index, g);
PredecessorMap predecessorMap(&predecessors[0], indexMap);
DistanceMap distanceMap(&distances[0], indexMap);
// Compute shortest paths from v0 to all vertices, and store the output in predecessors and distances
boost::dijkstra_shortest_paths(g, v0, boost::predecessor_map(predecessorMap).distance_map(distanceMap));
//////////////
*/
//////////////
IndexMap indexMap = get(boost::vertex_index, g);
DistanceMap distanceMap(&distances[0], indexMap);
PredecessorMap predecessorMap(&predecessors[0], indexMap);
boost::predecessor_map(predecessorMap).distance_map(distanceMap);
// Compute shortest paths from v0 to all vertices, and store the output in predecessors and distances
boost::dijkstra_shortest_paths(g, v0, boost::predecessor_map(predecessorMap));
//////////////
// Output results
std::cout << "distances and parents:" << std::endl;
NameMap nameMap = get(boost::vertex_name, g);
BGL_FORALL_VERTICES(v, g, Graph)
{
std::cout << "distance(" << nameMap[v0] << ", " << nameMap[v] << ") = " << distanceMap[v] << ", ";
std::cout << "predecessor(" << nameMap[v] << ") = " << nameMap[predecessorMap[v]] << std::endl;
}
