Question

我是boost编程的新手，但我希望在顶点着色时使用boost graph lib。

我已经阅读了boost / graph / smallest_last_ordering.hpp中的smallest_last_vertex_ordering的帮助文档和源代码。但我不知道如何构造函数smallest_last_vertex_ordering的参数。

这是smallest_last_vertex_ordering的定义：

template <class VertexListGraph, class Order, class Degree, class Marker>
  void 
  smallest_last_vertex_ordering(const VertexListGraph& G, Order order, 
                            Degree degree, Marker marker) {
    typedef typename boost::graph_traits<VertexListGraph> GraphTraits;
    typedef typename GraphTraits::vertex_descriptor Vertex;
    //typedef typename GraphTraits::size_type size_type;
    typedef std::size_t size_type;

    const size_type num = num_vertices(G);

    typedef typename boost::property_map<VertexListGraph, vertex_index_t>::type ID;
    typedef bucket_sorter<size_type, Vertex, Degree, ID> BucketSorter;

    BucketSorter degree_bucket_sorter(num, num, degree,  
                                  get(vertex_index,G));

    smallest_last_vertex_ordering(G, order, degree, marker, degree_bucket_sorter);
 }

你能告诉我如何创建合适的Order，degree和Marker？

非常感谢。

Answer 1

查看实现Order似乎是一个property map，它将std :: size_t作为键，将vertex_descriptor作为value_type。 Degree和Marker是属性映射，其中vertex_descriptor为key，std :: size_t为value_type。最后两个映射仅在内部需要，这就是为什么只有两个参数（图形和顺序属性映射）的重载的原因。

以下是使用该重载和示例版本（以避免此算法不支持此循环的循环）的示例here的示例：

#include <iostream>
#include <string>

#include <boost/graph/adjacency_list.hpp>
#include <boost/property_map/shared_array_property_map.hpp> //this should be included from smallest_last_ordering.hpp
#include <boost/graph/smallest_last_ordering.hpp>

int main()
{
    typedef boost::adjacency_list<boost::vecS,boost::vecS,boost::directedS> Graph;
    typedef boost::graph_traits<Graph>::vertex_descriptor VertexDesc;

    Graph g;
    VertexDesc A=add_vertex(g);
    VertexDesc B=add_vertex(g);
    VertexDesc C=add_vertex(g);
    VertexDesc D=add_vertex(g);
    VertexDesc E=add_vertex(g);

    add_edge(A,C,g);
    add_edge(A,E,g);
    add_edge(C,B,g);
    add_edge(E,B,g);
    add_edge(C,D,g);
    add_edge(B,D,g);
    add_edge(E,D,g);

    boost::vector_property_map<VertexDesc> order;

    smallest_last_vertex_ordering(g, order);

    std::string names[]={"A","B","C","D","E"};

    for(std::size_t index=0; index<num_vertices(g); ++index)
    {
        std::cout << names[order[index]] <<  " ";
    }
    std::cout << std::endl;
}

这是一个使用四参数重载的版本，因此您可以看到另一种定义属性映射的方法：

#include <iostream>
#include <string>
#include <map>

#include <boost/graph/adjacency_list.hpp>
#include <boost/property_map/shared_array_property_map.hpp> //this should be included from smallest_last_ordering.hpp
#include <boost/graph/smallest_last_ordering.hpp>

int main()
{
    typedef boost::adjacency_list<boost::vecS,boost::vecS,boost::directedS> Graph;
    typedef boost::graph_traits<Graph>::vertex_descriptor VertexDesc;

    Graph g;
    VertexDesc A=add_vertex(g);
    VertexDesc B=add_vertex(g);
    VertexDesc C=add_vertex(g);
    VertexDesc D=add_vertex(g);
    VertexDesc E=add_vertex(g);

    add_edge(A,C,g);
    add_edge(A,E,g);
    add_edge(C,B,g);
    add_edge(E,B,g);
    add_edge(C,D,g);
    add_edge(B,D,g);
    add_edge(E,D,g);

    typedef std::map<std::size_t,VertexDesc> OrderMap;
    OrderMap order;
    boost::associative_property_map<OrderMap> order_prop_map(order);

    typedef std::map<VertexDesc,std::size_t> Map;
    Map degree;
    Map marker;
    boost::associative_property_map<Map> degree_prop_map(degree);
    boost::associative_property_map<Map> marker_prop_map(marker);

    smallest_last_vertex_ordering(g, order_prop_map, degree_prop_map, marker_prop_map);

    //another alternative
    // std::vector<VertexDesc> order(num_vertices(g));
    // std::vector<std::size_t> degree(num_vertices(g));
    // std::vector<std::size_t> marker(num_vertices(g));
    // smallest_last_vertex_ordering(g, make_iterator_property_map(&order[0],boost::identity_property_map()), make_iterator_property_map(&degree[0],get(boost::vertex_index,g)), make_iterator_property_map(&marker[0],get(boost::vertex_index,g)));

    std::string names[]={"A","B","C","D","E"};

    for(std::size_t index=0; index<num_vertices(g); ++index)
    {
        std::cout << names[order[index]] <<  "(" << degree[order[index]] << "," << marker[order[index]] << ") ";
    }
    std::cout << std::endl;
}

任何人都可以给我一个在boost :: graph中使用smallest_last_vertex_ordering的例子吗？

1 个答案: