BGL - 如何在捆绑属性图中使用 BFS 记录距离？

Question

我正在尝试做一些简单的事情，比如获取一个节点到所有其他节点的距离，但我没有正确了解如何将breadth_first_search与我的图表一起使用......我遇到了很多编译错误我不明白为什么。

我什至尝试了其他问题中提出的解决方案，但它们对我不起作用

有人能帮我吗？

释义：

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;

最小的例子：

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;
}

编译错误：

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

两个问题

问题一：顶点索引

breadth_first_search 的记录要求包括顶点索引。 由于您使用基于节点的容器选择器 ( listS )，因此没有隐式索引，因此您应该提供一个：

注意：如果您使用此默认值，请确保您的图形具有内部 vertex_index 属性。 例如，带有 VertexList=listS 的 adjacency_list 没有内部 vertex_index 属性

这是一个显示vecS有效的简化示例：

在编译器资源管理器上运行

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));
}

现在将vecS更改为listS ：

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

没有按预期编译 ( Live )。 所以我们可以提供一个外部的临时索引： 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));

即使有独特的优势（ setS ， Live ），它仍然可以编译。

现在，让我们记录距离。

问题2：距离Map键

距离 map 的键必须是顶点描述符。¹

你可以看出是因为编译错误表明 distance_recorder 试图调用：

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

其中v和u是顶点描述符（ m_distance是您提供的距离属性图）。

两种解决方案

• 您可以再次使用关联 map： Live

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

• 您可以通过临时顶点索引投影键来修复属性映射： 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 实际上它看起来像有一个复制粘贴错误，因为该页面错误地声称值类型也需要是顶点描述符。 那是（显然？）从文档中为predecessor_recorder复制粘贴...