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[英]Using Boost Graph Library (BGL) to identify connected components
[英]BGL custom graph connected_components
我正在尝试使用boost图库的connected_components
算法。 我有一个数据结构以不同的格式定义这样的图形,我想避免将图形复制到BGL的图形类型,例如adjacency_list
。 因此我使用graph_traits
让BGL知道如何直接在我的图形结构上操作。 下面是一个简化的例子,展示了我面对实际数据时遇到的同样问题:
#include <vector>
#include <map>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/connected_components.hpp>
namespace myns {
struct MyGraph {
using VertsContainer = std::vector<std::string>;
using Edge = std::pair<std::string, std::string>;
using EdgesContainer = std::vector<Edge>;
VertsContainer verts;
EdgesContainer edges;
void get_connected_components();
};
}
namespace boost
{
template<>
struct graph_traits<myns::MyGraph> {
/////////////////////////////////
// Graph concept
/////////////////////////////////
using vertex_descriptor = myns::MyGraph::VertsContainer::value_type;
using edge_descriptor = myns::MyGraph::EdgesContainer::value_type;
using directed_category = boost::undirected_tag;
using edge_parallel_category = boost::disallow_parallel_edge_tag;
struct traversal_category : boost::vertex_list_graph_tag, boost::incidence_graph_tag {};
/////////////////////////////////
// Incidence graph concept
/////////////////////////////////
using out_edge_iterator = myns::MyGraph::EdgesContainer::const_iterator;
using degree_size_type = std::size_t;
// out_edges(v, g)
// source(e, g)
// target(e, g)
// out_degree(v, g)
/////////////////////////////////
// Adjacency graph concept
/////////////////////////////////
using adjacency_iterator = myns::MyGraph::VertsContainer::const_iterator;
// adjacent_vertices(v, g)
/////////////////////////////////
// Vertex list graph concept
/////////////////////////////////
using vertex_iterator = myns::MyGraph::VertsContainer::const_iterator;
using vertices_size_type = std::size_t;
// vertices(g)
// num_vertices(g)
};
} // namespace boost
namespace myns
{
boost::graph_traits<myns::MyGraph>::vertex_descriptor
source(const boost::graph_traits<myns::MyGraph>::edge_descriptor& e, const myns::MyGraph& g)
{
return e.first;
}
boost::graph_traits<myns::MyGraph>::vertex_descriptor
target(const boost::graph_traits<myns::MyGraph>::edge_descriptor& e, const myns::MyGraph& g)
{
return e.second;
}
std::pair<boost::graph_traits<myns::MyGraph>::out_edge_iterator, boost::graph_traits<myns::MyGraph>::out_edge_iterator>
out_edges(const boost::graph_traits<myns::MyGraph>::vertex_descriptor& v, const myns::MyGraph& g)
{
return{g.edges.begin(), g.edges.end()};
}
boost::graph_traits<myns::MyGraph>::degree_size_type
out_degree(const boost::graph_traits<myns::MyGraph>::vertex_descriptor& v, const myns::MyGraph& g)
{
return g.edges.size();
}
std::pair<boost::graph_traits<myns::MyGraph>::adjacency_iterator, boost::graph_traits<myns::MyGraph>::adjacency_iterator>
adjacent_vertices(const boost::graph_traits<myns::MyGraph>::vertex_descriptor& v, const myns::MyGraph& g)
{
return{g.verts.begin(), g.verts.end()};
}
std::pair<boost::graph_traits<myns::MyGraph>::vertex_iterator, boost::graph_traits<myns::MyGraph>::vertex_iterator>
vertices(const myns::MyGraph& g)
{
return{g.verts.begin(), g.verts.end()};
}
boost::graph_traits<myns::MyGraph>::vertices_size_type
num_vertices(const myns::MyGraph& g)
{
return g.verts.size();
}
} // namespace myns
static void _test_concepts()
{
BOOST_CONCEPT_ASSERT((boost::IncidenceGraphConcept<myns::MyGraph>));
BOOST_CONCEPT_ASSERT((boost::VertexListGraphConcept<myns::MyGraph>));
}
void myns::MyGraph::get_connected_components()
{
_test_concepts();
auto connectedComponentsMap = std::map<std::string, int>{};
boost::associative_property_map< std::map<std::string, int> > comp_prop_map(connectedComponentsMap);
boost::connected_components(*this, comp_prop_map);
}
int main()
{
myns::MyGraph().get_connected_components();
}
我得到的错误是:
In file included from /usr/local/include/boost/graph/graph_traits.hpp:18:
/usr/local/include/boost/mpl/eval_if.hpp:38:26: error: no type named 'type' in 'boost::no_property'
typedef typename f_::type type;
~~~~~~~~~~~~~^~~~
完整的错误信息和现场的代码在这里 。
我错过了什么?
您缺少color_map或vertex_index_map。 由于默认参数,Boost.Graph库中的算法根据它们的调用方式对图形施加了进一步的要求(您可以在算法文档中看到这些参数)。 在调用中,您将颜色贴图保留在外,因此算法使用其默认颜色贴图。 它试图通过使用boost::get(boost::vertex_index_t, const GraphType&)
来获取图形的索引图。 由于您的图形没有顶点索引属性,因此会发生错误。 您可以像在此处一样定义所需的get
函数(尽管使用当前的vertex_descriptor有点困难)或者只是创建自己的颜色映射并在之后忽略它。
完整的例子
#include <iostream>
#include <vector>
#include <map>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/connected_components.hpp>
namespace myns {
struct MyGraph {
using VertsContainer = std::vector<std::string>;
using Edge = std::pair<std::string, std::string>;
using EdgesContainer = std::vector<Edge>;
VertsContainer verts;
EdgesContainer edges;
void get_connected_components();
};
}
namespace boost
{
template<>
struct graph_traits<myns::MyGraph> {
/////////////////////////////////
// Graph concept
/////////////////////////////////
using vertex_descriptor = myns::MyGraph::VertsContainer::value_type;
using edge_descriptor = myns::MyGraph::EdgesContainer::value_type;
using directed_category = boost::undirected_tag;
using edge_parallel_category = boost::disallow_parallel_edge_tag;
struct traversal_category : boost::vertex_list_graph_tag, boost::incidence_graph_tag {};
static vertex_descriptor null_vertex(){ return {}; } //ADDED
/////////////////////////////////
// Incidence graph concept
/////////////////////////////////
using out_edge_iterator = myns::MyGraph::EdgesContainer::const_iterator;
using degree_size_type = std::size_t;
// out_edges(v, g)
// source(e, g)
// target(e, g)
// out_degree(v, g)
/////////////////////////////////
// Adjacency graph concept
/////////////////////////////////
using adjacency_iterator = myns::MyGraph::VertsContainer::const_iterator;
// adjacent_vertices(v, g)
/////////////////////////////////
// Vertex list graph concept
/////////////////////////////////
using vertex_iterator = myns::MyGraph::VertsContainer::const_iterator;
using vertices_size_type = std::size_t;
// vertices(g)
// num_vertices(g)
};
} // namespace boost
namespace myns
{
boost::graph_traits<myns::MyGraph>::vertex_descriptor
source(const boost::graph_traits<myns::MyGraph>::edge_descriptor& e, const myns::MyGraph& g)
{
return e.first;
}
boost::graph_traits<myns::MyGraph>::vertex_descriptor
target(const boost::graph_traits<myns::MyGraph>::edge_descriptor& e, const myns::MyGraph& g)
{
return e.second;
}
std::pair<boost::graph_traits<myns::MyGraph>::out_edge_iterator, boost::graph_traits<myns::MyGraph>::out_edge_iterator>
out_edges(const boost::graph_traits<myns::MyGraph>::vertex_descriptor& v, const myns::MyGraph& g)
{
return{g.edges.begin(), g.edges.end()};
}
boost::graph_traits<myns::MyGraph>::degree_size_type
out_degree(const boost::graph_traits<myns::MyGraph>::vertex_descriptor& v, const myns::MyGraph& g)
{
return g.edges.size();
}
std::pair<boost::graph_traits<myns::MyGraph>::adjacency_iterator, boost::graph_traits<myns::MyGraph>::adjacency_iterator>
adjacent_vertices(const boost::graph_traits<myns::MyGraph>::vertex_descriptor& v, const myns::MyGraph& g)
{
return{g.verts.begin(), g.verts.end()};
}
std::pair<boost::graph_traits<myns::MyGraph>::vertex_iterator, boost::graph_traits<myns::MyGraph>::vertex_iterator>
vertices(const myns::MyGraph& g)
{
return{g.verts.begin(), g.verts.end()};
}
boost::graph_traits<myns::MyGraph>::vertices_size_type
num_vertices(const myns::MyGraph& g)
{
return g.verts.size();
}
} // namespace myns
static void _test_concepts()
{
BOOST_CONCEPT_ASSERT((boost::IncidenceGraphConcept<myns::MyGraph>));
BOOST_CONCEPT_ASSERT((boost::VertexListGraphConcept<myns::MyGraph>));
}
void myns::MyGraph::get_connected_components()
{
_test_concepts();
auto connectedComponentsMap = std::map<std::string, int>{};
boost::associative_property_map< std::map<std::string, int> > comp_prop_map(connectedComponentsMap);
auto colorMap = std::map<std::string, boost::default_color_type>{}; //ADDED
boost::associative_property_map< std::map<std::string, boost::default_color_type> > color_prop_map(colorMap); //ADDED
boost::connected_components(*this, comp_prop_map, boost::color_map(color_prop_map)); //ADDED
}
int main()
{
myns::MyGraph().get_connected_components();
std::cout << "Yay" << std::endl;
}
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