Question

我是boost图库的新手，我正在尝试使用boost图库找到Graph中从一个顶点到另一个顶点的最短路径。我找到了一些关于如何使用前任地图的说明，但这对我来说不起作用。当我尝试调用p [some_vertex]时，我收到一条错误，指出[]运算符未定义。有人能告诉我为什么以及我做错了什么？

typedef property<edge_weight_t, double, property<edge_index_t, tElementIDVector>> tEdgeProperty;
typedef property<vertex_index_t, tElementID> VertexIDPorperty;
typedef adjacency_list<vecS, setS, directedS, VertexIDPorperty, tEdgeProperty> tGraph;

typedef tGraph::vertex_descriptor tVertex;
typedef tGraph::edge_descriptor tEdge;

vector<tVertex> p(num_vertices(graph));
vector<double> d(num_vertices(graph));
// call dijkstra algorithm from boost to find shortest path
dijkstra_shortest_paths(graph, s,
    predecessor_map(&p[0]).
    distance_map(boost::make_iterator_property_map(d.begin(), get(boost::vertex_index, graph))));

//find path from start to end vertex
list<tVertex> pathVertices;
tVertex current = goal;
while (current != start)
{
    pathVertices.push_front(current);
    current = p[current];     //this is where the error occures
}

Answer 1

来自cppreference：

的std ::矢量::操作符[]

reference       operator[]( size_type pos );
const_reference operator[]( size_type pos ) const;

接受 size_t 指定向量元素的位置。

但是，在您的代码中，current的类型为tVertex。

如果您想将operator[]与tVertex参数一起使用，则应覆盖它。

Answer 2

我无法让你的想法发挥作用，现在也不得不做出一些其他的改变，这就是为什么我现在把我的前任地图改为：

typedef boost::property_map < tGraph, boost::vertex_index_t >::type IndexMap;
typedef boost::iterator_property_map < tVertex*, IndexMap, tVertex, tVertex& > PredecessorMap;
tVertex s = start;
IndexMap indexMap = get(vertex_index, graph);
vector<tVertex> p(num_vertices(graph));
PredecessorMap predecessorMap(&p[0], indexMap);
vector<double> d(num_vertices(graph));

// call dijkstra algorithm from boost to find shortest path
dijkstra_shortest_paths(graph, s, predecessor_map(predecessorMap).distance_map(boost::make_iterator_property_map(d.begin(), get(boost::vertex_index, graph))));
//find path from start to end vertex
list<tVertex> pathVertices;
tVertex current = goal;
while (current != start)
{
    pathVertices.push_front(current);
    current = predecessorMap[current];
}

这实际上现在有效：）

使用Dijkstra在增强图中找到最短路径

2 个答案: