Question

如何使用BGL计算过滤图的连通分量？我创建了一个工作过滤器来检查名为“alive”的自定义顶点属性，并仅返回connected_components上的“活”顶点，但filtered_graph扼流圈。我认为这与过滤后的图形具有非连续顶点id这一事实有关，因此现在不再定义已定义的operator[]，但我不确定为什么或如何围绕它进行编码。

typedef boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, VertexProperties> Graph;
typedef boost::property_map<Graph, ::vertex_alive_t>::type AliveMap;

template <typename AliveMap>
struct vertex_is_alive {
  vertex_is_alive() { }
  vertex_is_alive(AliveMap alive) : m_alive(alive) { }
  template <typename Vertex>
  bool operator()(const Vertex& v) const {
    return boost::get(m_alive,v) == STILL_ALIVE_CODE;
  }
  AliveMap m_alive;
};

Graph G;
//generate G...
int N = boost::num_vertices(G);
vector<int> component(N);
int num = boost::connected_components(G, &component[0]);
//do something with component and play around with vertex_alive statuses...this part works fine.
vertex_is_alive<AliveMap> filter(boost::get(::vertex_alive_t(), G));
boost::filtered_graph<Graph, vertex_is_alive<AliveMap> > fG (G, filter); 
int num = boost::connected_components(fG, &component[0]);
//this makes it choke

我得到的错误信息是（删除家谱）：

/usr/local/include/boost/property_map/property_map.hpp:354:56: error: no match for ‘operator[]’ in ‘((const boost::vec_adj_list_vertex_property_map<boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, boost::property<vertex_alive_t, unsigned int> >, boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, boost::property<vertex_alive_t, unsigned int> >*, unsigned int, unsigned int&, vertex_alive_t>&)pa)[k]’
/usr/local/include/boost/property_map/property_map.hpp:354:56: note: candidate is:
In file included from /usr/local/include/boost/graph/adjacency_list.hpp:245:0,
                 from main.cpp:1:
/usr/local/include/boost/graph/detail/adjacency_list.hpp:2465:24: note: Reference boost::vec_adj_list_vertex_property_map<Graph, GraphPtr, ValueType, Reference, Tag>::operator[](boost::vec_adj_list_vertex_property_map<Graph, GraphPtr, ValueType, Reference, Tag>::key_type) const [with Graph = boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, boost::property<vertex_alive_t, unsigned int> >; GraphPtr = boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, boost::property<vertex_alive_t, unsigned int> >*; ValueType = unsigned int; Reference = unsigned int&; Tag = vertex_alive_t; boost::vec_adj_list_vertex_property_map<Graph, GraphPtr, ValueType, Reference, Tag>::key_type = unsigned int]
/usr/local/include/boost/graph/detail/adjacency_list.hpp:2465:24: note:   no known conversion for argument 1 from ‘const boost::detail::edge_desc_impl<boost::undirected_tag, unsigned int>’ to ‘boost::vec_adj_list_vertex_property_map<boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, boost::property<vertex_alive_t, unsigned int> >, boost::adjacency_list<boost::hash_mapS, boost::vecS, boost::undirectedS, boost::property<vertex_alive_t, unsigned int> >*, unsigned int, unsigned int&, vertex_alive_t>::key_type {aka unsigned int}’

Answer 1

你应该使用boost :: filtered_graph＆gt; fG（G，boost :: keep_all（），filter）;.过滤后的图表的签名为filtered_graph<Graph, EdgePredicate, VertexPredicate>，因此您使用顶点过滤器作为边缘过滤器。错误中的最后一行意味着boost :: get（m_alive，x）要求x是顶点描述符（unsigned int）并且它正在传递边描述符（const boost::detail::edge_desc_impl<boost::undirected_tag, unsigned int>）。

找到过滤图的连通分量

1 个答案: