我对 Boost 图很陌生.我正在尝试修改一个示例来查找使用 VertexList = vecS 的 Dijkstra 最短路径算法.我将顶点容器更改为 ListS.我了解到如果我们使用 listS，我们必须提供我们自己的 vertex_index 算法才能工作.
I am quite new to Boost graph. I am trying to adapt an example for finding Dijkstra Shortest Path algorithm which used VertexList = vecS. I changed the vertex container to ListS. I learned that we have to provide our own vertex_index for the algorithm to work if we use listS.
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::property<boost::vertex_index_t, int> IndexProperty;
typedef boost::adjacency_list < boost::listS, boost::listS, boost::directedS,
NameProperty, WeightProperty > Graph;
typedef boost::graph_traits < Graph >::vertex_descriptor Vertex;
typedef boost::graph_traits <Graph>::vertex_iterator Viter;
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;
Graph g;
Vertex v0 = boost::add_vertex(std::string("v0"), g);
Vertex v1 = boost::add_vertex(std::string("v1"), g);
Vertex v2 = boost::add_vertex(std::string("v2"), g);
Vertex v3 = boost::add_vertex(std::string("v3"), g);
Weight weight0 = 5;
Weight weight1 = 3;
Weight weight2 = 2;
Weight weight3 = 4;
boost::add_edge(v0, v1, weight0, g);
boost::add_edge(v1, v3, weight1, g);
boost::add_edge(v0, v2, weight2, g);
boost::add_edge(v2, v3, weight3, g);
std::vector<Vertex> predecessors(boost::num_vertices(g)); // To store parents
std::vector<Weight> distances(boost::num_vertices(g)); // To store distances
IndexMap indexMap; // = boost::get(boost::vertex_index, g);
NameMap name;
Viter i, iend;
//Create our own vertex index. This is what I changed in the original code
int c = 0;
for (boost::tie(i, iend) = vertices(g); i != iend; ++i, ++c) {
indexMap[*i] = c; // **Error points to this line**
name[*i] = 'A' + c;
}
PredecessorMap predecessorMap(&predecessors[0], indexMap);
DistanceMap distanceMap(&distances[0], indexMap);
boost::dijkstra_shortest_paths(g, v0, boost::distance_map(distanceMap).predecessor_map(predecessorMap));
// Extract a shortest path
std::cout << std::endl;
typedef std::vector<Graph::edge_descriptor> PathType;
PathType path;
Vertex v = v3;
for(Vertex u = predecessorMap[v];
u != v; // Keep tracking the path until we get to the source
v = u, u = predecessorMap[v]) // Set the current vertex to the current predecessor, and the predecessor to one level up
{
std::pair<Graph::edge_descriptor, bool> edgePair = boost::edge(u, v, g);
Graph::edge_descriptor edge = edgePair.first;
path.push_back( edge );
}
// Write shortest path
std::cout << "Shortest path from v0 to v3:" << std::endl;
float totalDistance = 0;
for(PathType::reverse_iterator pathIterator = path.rbegin(); pathIterator != path.rend(); ++pathIterator)
{
std::cout << name[boost::source(*pathIterator, g)] << " -> " << name[boost::target(*pathIterator, g)]
<< " = " << boost::get( boost::edge_weight, g, *pathIterator ) << std::endl;
}
std::cout << std::endl;
std::cout << "Distance: " << distanceMap[v3] << std::endl;
return EXIT_SUCCESS;
}
我收到以下错误:
/spvec.cpp:62:20: 错误:'index.boost::adj_list_vertex_property_map::operator[] [with Graph = boost::adjacency_list >, boost::property > 中的'operator=' 不匹配，ValueType = boost::detail::error_property_not_found, Reference = boost::detail::error_property_not_found&, Tag = boost::vertex_index_t, boost::adj_list_vertex_property_map::key_type = void*](i.std::_List_iterator<_Tp>::operator* with _Tp = void*, _Tp& = void*&) = c'
/spvec.cpp:62:20: error: no match for ‘operator=’ in ‘index.boost::adj_list_vertex_property_map::operator[] [with Graph = boost::adjacency_list >, boost::property >, ValueType = boost::detail::error_property_not_found, Reference = boost::detail::error_property_not_found&, Tag = boost::vertex_index_t, boost::adj_list_vertex_property_map::key_type = void*](i.std::_List_iterator<_Tp>::operator* with _Tp = void*, _Tp& = void*&) = c’
我确定我在创建自己的顶点索引时犯了一个错误.但无法准确找出问题所在.有没有人对我做错了什么有一些建议..
I am sure I made a mistake in creating my own vertex index. But couldnt find out exactly whats the issue. Does anyone have some suggestions on what I am doing wrong..
BGL 实际上有一个使用 dijkstra_shortest_paths 和 listS/listS 的例子，但它没有从 HTML 文档中链接到:http://www.boost.org/doc/libs/release/libs/graph/example/dijkstra-example-listS.cpp
BGL actually has an example of using dijkstra_shortest_paths with listS/listS, but it's not linked to from the HTML documentation: http://www.boost.org/doc/libs/release/libs/graph/example/dijkstra-example-listS.cpp
错误消息试图告诉您什么(error: no match for 'operator=' in 'index.boost::adj_list_vertex_property_map...ValueType = boost::detail::error_property_not_found...) 是 vertex_index_t 属性没有每个顶点的存储，这是 adj_list_vertex_property_map 需要的.要解决此问题，您可以更改 Graph typedef 以包含 vertex_index_t 属性的每个顶点存储或使用外部"属性映射例如associative_property_map.
What the error message is trying to tell you (error: no match for ‘operator=’ in ‘index.boost::adj_list_vertex_property_map...ValueType = boost::detail::error_property_not_found...) is that there is no per-vertex storage for the vertex_index_t property, which is what adj_list_vertex_property_map needs. To fix the problem you can either change your Graph typedef to include per-vertex storage for the vertex_index_t property or use an "external" property map such as associative_property_map.
dijkstra-example-listS.cpp 示例使用了更改图形typedef 的方法.要在您的代码中使用这种方法，您可以定义:
The dijkstra-example-listS.cpp example uses the approach of changing the graph typedef. To use this approach in your code, you could define:
typedef boost::adjacency_list <boost::listS, boost::listS, boost::directedS,
boost::property<boost::vertex_name_t, std::string, boost::property<boost::vertex_index_t, int> >,
boost::property<boost::edge_weight_t, Weight> > Graph;
这篇关于提升图中 VertexList = ListS 的 Dijkstra 最短路径的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！