[英]Dijkstra Shortest Path with VertexList = ListS in boost graph
I am quite new to Boost graph. 我对Boost图表很新。 I am trying to adapt an example for finding Dijkstra Shortest Path algorithm which used VertexList = vecS.
我正在尝试调整一个例子来找到使用VertexList = vecS的Dijkstra最短路径算法。 I changed the vertex container to ListS.
我将顶点容器更改为ListS。 I learned that we have to provide our own vertex_index for the algorithm to work if we use listS.
我了解到,如果我们使用listS,我们必须提供自己的vertex_index才能使算法正常工作。
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;
}
I get the following error: 我收到以下错误:
/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' /spvec.cpp:62:20:错误:'index.boost :: adj_list_vertex_property_map :: operator []中没有匹配'operator ='[与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'
I am sure I made a mistake in creating my own vertex index. 我确信我在创建自己的顶点索引时犯了一个错误。 But couldn´t find out exactly what´s the issue.
但无法确切地找出问题所在。 Does anyone have some suggestions on what I am doing wrong..
有没有人对我做错了什么有一些建议..
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 BGL实际上有一个使用
dijkstra_shortest_paths
和listS / listS的例子,但它没有链接到HTML文档: http : //www.boost.org/doc/libs/release/libs/graph/example/dijkstra-example-listS的.cpp
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. 错误消息试图告诉你的内容(
error: no match for 'operator=' in 'index.boost:: adj_list_vertex_property_map ...ValueType = boost::detail:: error_property_not_found ...
)是没有 - vertex_index_t
属性的顶点存储,这是adj_list_vertex_property_map
需要的。 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
. 要解决此问题,您可以更改
Graph
typedef
以包含vertex_index_t
属性的每顶点存储,或使用“external”属性映射(例如associative_property_map
。
The dijkstra-example-listS.cpp
example uses the approach of changing the graph typedef
. dijkstra-example-listS.cpp
示例使用更改图形typedef
。 To use this approach in your code, you could define: 要在代码中使用此方法,您可以定义:
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;
If somebody is interested in the solution, Creating an associative_property_map as suggested in the previous answer solved the issue: 如果有人对该解决方案感兴趣,请按照上一个答案中的建议创建一个associative_property_map解决了这个问题:
typedef std::map<vertex_desc, size_t>IndexMap;
IndexMap mapIndex;
boost::associative_property_map<IndexMap> propmapIndex(mapIndex);
//indexing the vertices
int i=0;
BGL_FORALL_VERTICES(v, g, pGraph)
{
boost::put(propmapIndex, v, i++);
}
Then pass this Vertex index map to the dijkstra_shortest_paths() call as a named parameter. 然后将此顶点索引映射作为命名参数传递给dijkstra_shortest_paths()调用。 PS: BGL_FORALL_VERTICES() is defined in < boost/graph/iteration/iteration_macros.hpp >
PS:BGL_FORALL_VERTICES()在<boost / graph / iteration / iteration_macros.hpp>中定义
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