使用 vertex_descriptor 提升图打印或迭代顶点

Question

构建增强图，其中添加了边缘区域（如下）并且 v1 定义为

gm->create_edge(v1,v2,1); 
boost::graph_traits<Graph>::vertex_descriptor v1 = gm-> create_vertex("one",1,1);

如何打印或枚举顶点使用？：

boost::graph_traits<Graph>::vertex_descriptor vd;

这允许我打印顶点 ID：

Graph::vertex_iterator v, vend, vnext; 
for (boost::tie(v, vend) = vertices(gm->g); v != vend; ++v)
    std::cout << gm->g[*v].id << ", "  << gm->g[*v].color << ", ";

我有一个节点度的函数，它需要一个顶点描述符，那么，我该如何传递它？

gm->degree( takes vertex_descriptor )?

这很接近。

Answer 1

vertices(g) returns 一个迭代器对。间接迭代器给出了描述符。在你自己的例子中 v 是 vertex_iterator 所以 *v 是 vertex_descriptor.

让我们使用 Boost 的 degree 函数——它也有一个描述符：

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#include <boost/graph/adjacency_list.hpp>

namespace MyProgram {
    using namespace boost;
    struct VertexProps { int id; default_color_type color; };

    using Graph = adjacency_list<vecS, vecS, directedS, VertexProps>;

    Graph make_sample_graph();
}

#include <iostream>

int main() {
    using MyProgram::Graph;
    Graph g = MyProgram::make_sample_graph();

    Graph::vertex_iterator v, vend;
    for (boost::tie(v, vend) = vertices(g); v != vend; ++v) {
        std::cout << "Vertex descriptor #" << *v 
             << " degree:" << degree(*v, g)
             << " id:"     << g[*v].id
             << " color:"  << g[*v].color
             << "\n";
    }
}

不过我更愿意使用 ranged-for：

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for (auto vd : boost::make_iterator_range(vertices(g))) {
    std::cout << "Vertex descriptor #" << vd 
         << " degree:" << degree(vd, g)
         << " id:"     << g[vd].id
         << " color:"  << g[vd].color
         << "\n";
}

对于 make_sample_graph() 的完整性：

namespace MyProgram {
    Graph make_sample_graph() {
        Graph g(10);
        for (auto vd : boost::make_iterator_range(vertices(g)))
            g[vd] = { int(vd)*100, {} };

        add_edge(1,2,g);
        add_edge(2,3,g);
        add_edge(4,5,g);
        add_edge(4,6,g);
        add_edge(6,7,g);

        return g;
    }
}

打印：

Vertex descriptor #0 degree:0 id:0 color:0
Vertex descriptor #1 degree:1 id:100 color:0
Vertex descriptor #2 degree:2 id:200 color:0
Vertex descriptor #3 degree:1 id:300 color:0
Vertex descriptor #4 degree:2 id:400 color:0
Vertex descriptor #5 degree:1 id:500 color:0
Vertex descriptor #6 degree:2 id:600 color:0
Vertex descriptor #7 degree:1 id:700 color:0
Vertex descriptor #8 degree:0 id:800 color:0
Vertex descriptor #9 degree:0 id:900 color:0

使用 vertex_descriptor 提升图打印或迭代顶点

print or iterate over the vertices with vertex_descriptor boost graph

c++

boost

graph

descriptor

vertex