BGL - 如何在捆绑属性图中使用 BFS 记录距离？

Question

I'm trying to do something as simple as getting the distances from one node to all the others, but I'm not getting it right about how to use the breadth_first_search with my graph... I'm getting a lot of compilation errors and I don't undestand why.

I even tried the solutions proposed in other questions, but they didn't work for me

Can some one help me?

Definitions:

class Position {
   public:
    Position() : x(0), y(0) {}
    Position(int a, int b) : x(a), y(b) {}

    // operator overrides
    
    int x, y;
};

struct Group {
    Group(Position pos, short c, short s) : position(pos), color(c), size(s) {}
    Group() {}
    Position position;
    short color;
    short size;
};

inline bool operator==(const Group& g1, const Group& g2) {
    return g1.position == g2.position;
};
inline bool operator!=(const Group& g1, const Group& g2) {
    return g1.position != g2.position;
};

typedef boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property> Graph;

typedef boost::graph_traits<Graph>::vertex_descriptor VertexDescriptor;

Minimal example:

int main() {
    Graph graph;

    // build graph

    VertexDescriptor v = *boost::vertices(graph).first;
    std::vector<int> distances(boost::num_vertices(graph));

    boost::breadth_first_search(graph, v, boost::visitor( boost::make_bfs_visitor( boost::record_distances(distances.begin(), boost::on_tree_edge{}))));

    return 0;
}

Compilation error:

In file included from /usr/include/boost/graph/adjacency_list.hpp:223,
                 from src/../include/graph.hpp:4,
                 from src/main.cpp:3:
/usr/include/boost/graph/detail/adjacency_list.hpp: In instantiation of ‘struct boost::adj_list_any_vertex_pa::bind_<boost::vertex_index_t, boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, Group>’:
/usr/include/boost/graph/detail/adjacency_list.hpp:2617:12:   required from ‘struct boost::detail::adj_list_choose_vertex_pa<boost::vertex_index_t, boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, Group>’
/usr/include/boost/graph/detail/adjacency_list.hpp:2754:12:   required from ‘struct boost::adj_list_vertex_property_selector::bind_<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, Group, boost::vertex_index_t>’
/usr/include/boost/graph/properties.hpp:201:12:   required from ‘struct boost::detail::vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::vertex_index_t>’
/usr/include/boost/graph/properties.hpp:212:10:   required from ‘struct boost::property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::vertex_index_t, void>’
/usr/include/boost/mpl/eval_if.hpp:38:31:   recursively required from ‘struct boost::mpl::eval_if<mpl_::bool_<true>, boost::detail::const_type_as_type<boost::property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::vertex_index_t, void> >, boost::property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::vertex_index_t, void> >’
/usr/include/boost/mpl/eval_if.hpp:38:31:   required from ‘struct boost::mpl::eval_if<boost::is_same<boost::param_not_found, boost::param_not_found>, boost::mpl::eval_if<mpl_::bool_<true>, boost::detail::const_type_as_type<boost::property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::vertex_index_t, void> >, boost::property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::vertex_index_t, void> >, boost::mpl::identity<boost::param_not_found> >’
/usr/include/boost/graph/named_function_params.hpp:273:12:   required from ‘struct boost::detail::choose_impl_result<mpl_::bool_<true>, boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>, boost::param_not_found, boost::vertex_index_t>’
/usr/include/boost/graph/named_function_params.hpp:309:3:   required by substitution of ‘template<class Param, class Graph, class PropertyTag> typename boost::detail::choose_impl_result<mpl_::bool_<true>, Graph, Param, PropertyTag>::type boost::choose_const_pmap(const Param&, const Graph&, PropertyTag) [with Param = boost::param_not_found; Graph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>; PropertyTag = boost::vertex_index_t]’
/usr/include/boost/graph/breadth_first_search.hpp:315:30:   required from ‘static void boost::detail::bfs_dispatch<boost::param_not_found>::apply(VertexListGraph&, typename boost::graph_traits<Graph>::vertex_descriptor, const boost::bgl_named_params<T, Tag, Base>&, boost::param_not_found) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>; P = boost::bfs_visitor<boost::distance_recorder<__gnu_cxx::__normal_iterator<int*, std::vector<int> >, boost::on_tree_edge> >; T = boost::graph_visitor_t; R = boost::no_property; typename boost::graph_traits<Graph>::vertex_descriptor = void*]’
/usr/include/boost/graph/breadth_first_search.hpp:343:35:   required from ‘void boost::breadth_first_search(const VertexListGraph&, typename boost::graph_traits<Graph>::vertex_descriptor, const boost::bgl_named_params<T, Tag, Base>&) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>; P = boost::bfs_visitor<boost::distance_recorder<__gnu_cxx::__normal_iterator<int*, std::vector<int> >, boost::on_tree_edge> >; T = boost::graph_visitor_t; R = boost::no_property; typename boost::graph_traits<Graph>::vertex_descriptor = void*]’
src/main.cpp:41:151:   required from here
/usr/include/boost/graph/detail/adjacency_list.hpp:2547:29: error: forming reference to void
 2547 |         typedef value_type& reference;
      |                             ^~~~~~~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2548:35: error: forming reference to void
 2548 |         typedef const value_type& const_reference;
      |                                   ^~~~~~~~~~~~~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2551:47: error: forming reference to void
 2551 |           <Graph, value_type, reference, Tag> type;
      |                                               ^~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2553:53: error: forming reference to void
 2553 |           <Graph, value_type, const_reference, Tag> const_type;
      |                                                     ^~~~~~~~~~
In file included from src/main.cpp:7:
/usr/include/boost/graph/breadth_first_search.hpp: In instantiation of ‘static void boost::detail::bfs_dispatch<boost::param_not_found>::apply(VertexListGraph&, typename boost::graph_traits<Graph>::vertex_descriptor, const boost::bgl_named_params<T, Tag, Base>&, boost::param_not_found) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>; P = boost::bfs_visitor<boost::distance_recorder<__gnu_cxx::__normal_iterator<int*, std::vector<int> >, boost::on_tree_edge> >; T = boost::graph_visitor_t; R = boost::no_property; typename boost::graph_traits<Graph>::vertex_descriptor = void*]’:
/usr/include/boost/graph/breadth_first_search.hpp:343:35:   required from ‘void boost::breadth_first_search(const VertexListGraph&, typename boost::graph_traits<Graph>::vertex_descriptor, const boost::bgl_named_params<T, Tag, Base>&) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>; P = boost::bfs_visitor<boost::distance_recorder<__gnu_cxx::__normal_iterator<int*, std::vector<int> >, boost::on_tree_edge> >; T = boost::graph_visitor_t; R = boost::no_property; typename boost::graph_traits<Graph>::vertex_descriptor = void*]’
src/main.cpp:41:151:   required from here
/usr/include/boost/graph/breadth_first_search.hpp:315:30: error: no matching function for call to ‘choose_const_pmap(const type&, boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Group, boost::no_property>&, boost::vertex_index_t)’
  315 |             choose_const_pmap(get_param(params, vertex_index),
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  316 |                               g, vertex_index)),
      |                               ~~~~~~~~~~~~~~~~
In file included from /usr/include/boost/graph/breadth_first_search.hpp:23,
                 from src/main.cpp:7:
/usr/include/boost/graph/named_function_params.hpp:309:3: note: candidate: ‘template<class Param, class Graph, class PropertyTag> typename boost::detail::choose_impl_result<mpl_::bool_<true>, Graph, Param, PropertyTag>::type boost::choose_const_pmap(const Param&, const Graph&, PropertyTag)’
  309 |   choose_const_pmap(const Param& p, const Graph& g, PropertyTag tag)
      |   ^~~~~~~~~~~~~~~~~
/usr/include/boost/graph/named_function_params.hpp:309:3: note:   substitution of deduced template arguments resulted in errors seen above

Answer 1

Two problems

Problem 1: Vertex Index

The documented requirements for breadth_first_search include a vertex index. Since you use a node-based container selector ( listS ) there is no implicit index, so you should provide one :

Note: if you use this default, make sure your graph has an internal vertex_index property. For example, adjacency_list with VertexList=listS does not have an internal vertex_index property

Here's a simplified example showing that vecS works:

Live On Compiler Explorer

using Graph =
    boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, Group>;
using V = Graph::vertex_descriptor;

int main() {
    Graph graph(10);

    V v = vertex(0, graph);

    auto vis = boost::default_bfs_visitor{};

    breadth_first_search(graph, v, visitor(vis));
}

Now changing vecS to listS :

using Graph =
    boost::adjacency_list<boost::vecS, boost::listS, boost::undirectedS, Group>;

doesn't compile ( Live ), as expected. So we could supply an external, temporary index: Live

std::map<V, int> tmp_index;
for (auto v : boost::make_iterator_range(vertices(graph)))
    tmp_index[v] = tmp_index.size();

auto index_map = boost::make_assoc_property_map(tmp_index);
breadth_first_search(graph, v, visitor(vis).vertex_index_map(index_map));

It still compiles even with unique edges ( setS , Live ).

Now, let's record distances.

Problem 2: Distance Map Keys

The keys of the distance map are required to be the vertex descriptor .¹

You can tell because the compilation error indicates that the distance_recorder tries to call:

put(m_distance, v, get(m_distance, u) + 1);

where v and u are vertex descriptors (and m_distance is the distance propertymap you supplied).

Two solutions

• You can use an associative map again: Live

   std::map<V, int> distances; auto vis = make_bfs_visitor(record_distances( boost::make_assoc_property_map(distances), boost::on_tree_edge{}));

• You can fix the propertymap by projecting the key through the temporary vertex index: Live

   auto index_map = boost::make_assoc_property_map(tmp_index); auto dist_map = make_safe_iterator_property_map(dist.begin(), dist.size(), index_map); auto vis = make_bfs_visitor(record_distances(dist_map, boost::on_tree_edge{}));

---

¹ Actually it looks like there was a copy paste error because that page incorrectly claims the value type needs to be the vertex-descriptor as well. That is (obviously?) copy-pasted from the docs for predecessor_recorder ...