是否可以使用 ::boost::write_graphviz 生成 DOT 子图？

例如，如果我在图 G 中创建一个子图 G0，我能否在 DOT 输出中得到如下内容:

graph G {
  subgraph G0 {
    ...
  }
  ...
}

最佳答案

我终于明白了子图的工作原理和如何使用 boost::write_graphviz 来实际打印这些。

第一个要求是在 boost 库源代码的注释中“半记录”:requires graph_name property。

然而，最令人惊讶的要求似乎是 detail::write_graphviz_subgraph 假定存在

• 顶点属性
• edge_attribute
• graph_vertex_attribute, graph_edge_attribute, graph_graph_attribute 图属性

属性。我认为这些要求可能非常严格，因为您的图形类型至少看起来像这样:

using Graph =
    adjacency_list<vecS, vecS, directedS, 
      property<vertex_attribute_t, GraphvizAttributes>,
      property<edge_index_t, int, property<edge_attribute_t, GraphvizAttributes> >,
      property<graph_name_t, std::string,
        property<graph_graph_attribute_t,  GraphvizAttributes,
        property<graph_vertex_attribute_t, GraphvizAttributes,
        property<graph_edge_attribute_t,   GraphvizAttributes>
      > > >
    >;

无论如何，很高兴演示如何使用它们来实际向 Graphviz 提供边/节点/(子)图属性，当然:

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template <typename SubGraph> SubGraph create_data()
{
    enum { A,B,C,D,E,F,N }; // main edges
    SubGraph main(N);

    SubGraph& sub1 = main.create_subgraph();
    SubGraph& sub2 = main.create_subgraph();

    auto A1 = add_vertex(A, sub1);
    auto B1 = add_vertex(B, sub1);

    auto E2 = add_vertex(E, sub2);
    auto C2 = add_vertex(C, sub2);
    auto F2 = add_vertex(F, sub2);

    add_edge(A1, B1, sub1);
    add_edge(E2, F2, sub2);
    add_edge(C2, F2, sub2);

    add_edge(E, B, main);
    add_edge(B, C, main);
    add_edge(B, D, main);
    add_edge(F, D, main);

    // setting some graph viz attributes
    get_property(main, graph_name) = "G0";
    get_property(sub1, graph_name) = "clusterG1";
    get_property(sub2, graph_name) = "clusterG2";

    get_property(sub1, graph_graph_attribute)["label"]              = "G1";
    /*extra*/get_property(sub1, graph_vertex_attribute)["shape"]    = "Mrecord";

    get_property(sub2, graph_graph_attribute)["label"]              = "G2";
    /*extra*/get_property(sub1, graph_vertex_attribute)["color"]    = "red";
    /*extra*/get_property(sub2, graph_graph_attribute)["fillcolor"] = "lightgray";
    /*extra*/get_property(sub2, graph_graph_attribute)["style"]     = "filled";
    /*extra*/get_property(sub2, graph_vertex_attribute)["shape"]    = "circle";

    return main;
}

那就是

int main() {
#ifdef GENERATE_RANDOM_GRAPHS
    auto g = generate_random<subgraph<Graph> >();
#else
    auto g = create_data<subgraph<Graph> >();
#endif

    for (auto vd : make_iterator_range(vertices(g))) {
        put(get(vertex_attribute, g), vd, 
                GraphvizAttributes{
                    {"label", name_for_index(vd)}
                });
    }

    write_graphviz(std::cout, g);
}

为了我自己的测试和理解，我还实现了 generate_random，它生成的图表如下:

完整程序

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#include <boost/graph/graphviz.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/subgraph.hpp>
#include <iostream>

using namespace boost;

//#define GENERATE_RANDOM_GRAPHS
#ifdef GENERATE_RANDOM_GRAPHS
#include <boost/graph/random.hpp> // in case you comment out the random graph creation code
#include <random>

template <typename SubGraph> SubGraph generate_random()
{
    std::mt19937 prng(std::random_device{}());
    SubGraph randomized(uniform_int<int>(10,20)(prng));

    auto subs = uniform_int<int>(1,5)(prng);
    while (subs--) randomized.create_subgraph();
    subs = boost::size(randomized.children());

    int offset = 0;
    for (auto& sub : make_iterator_range(randomized.children()))
    {
        for (size_t i = offset; i < num_vertices(randomized); i += subs) 
            add_vertex(i, sub);
        ++offset;
    }

    auto random_edges = [&](SubGraph& g) {
        uniform_int<typename SubGraph::vertex_descriptor> v(0, num_vertices(g) -1);
        for (size_t i = 1; i < 4; ++i)
            add_edge(v(prng), v(prng), g);
    };

    for (auto& sub : make_iterator_range(randomized.children()))
        random_edges(sub);
    random_edges(randomized);

    // setting some graph viz attributes
    get_property(randomized, graph_name) = "G0";

    offset = 0;
    for (auto& sub : make_iterator_range(randomized.children())) {
        ++offset;
        get_property(sub, graph_name) = "cluster" + std::to_string(offset);
        get_property(sub, graph_graph_attribute)["label"]    = "G" + std::to_string(offset);
    }

    return randomized;
}
#else

template <typename SubGraph> SubGraph create_data()
{
    enum { A,B,C,D,E,F,N }; // main edges
    SubGraph main(N);

    SubGraph& sub1 = main.create_subgraph();
    SubGraph& sub2 = main.create_subgraph();

    auto A1 = add_vertex(A, sub1);
    auto B1 = add_vertex(B, sub1);

    auto E2 = add_vertex(E, sub2);
    auto C2 = add_vertex(C, sub2);
    auto F2 = add_vertex(F, sub2);

    add_edge(A1, B1, sub1);
    add_edge(E2, F2, sub2);
    add_edge(C2, F2, sub2);

    add_edge(E, B, main);
    add_edge(B, C, main);
    add_edge(B, D, main);
    add_edge(F, D, main);

    // setting some graph viz attributes
    get_property(main, graph_name) = "G0";
    get_property(sub1, graph_name) = "clusterG1";
    get_property(sub2, graph_name) = "clusterG2";

    get_property(sub1, graph_graph_attribute)["label"]              = "G1";
    /*extra*/get_property(sub1, graph_vertex_attribute)["shape"]    = "Mrecord";

    get_property(sub2, graph_graph_attribute)["label"]              = "G2";
    /*extra*/get_property(sub1, graph_vertex_attribute)["color"]    = "red";
    /*extra*/get_property(sub2, graph_graph_attribute)["fillcolor"] = "lightgray";
    /*extra*/get_property(sub2, graph_graph_attribute)["style"]     = "filled";
    /*extra*/get_property(sub2, graph_vertex_attribute)["shape"]    = "circle";

    return main;
}
#endif

using GraphvizAttributes = 
    std::map<std::string, std::string>;

using Graph =
    adjacency_list<vecS, vecS, directedS, 
        property<vertex_attribute_t, GraphvizAttributes>,
        property<edge_index_t, int, property<edge_attribute_t, GraphvizAttributes> >,
        property<graph_name_t, std::string,
        property<graph_graph_attribute_t,  GraphvizAttributes,
        property<graph_vertex_attribute_t, GraphvizAttributes,
        property<graph_edge_attribute_t,   GraphvizAttributes>
        > > >
    >;

static std::string name_for_index(intmax_t index) {
    std::string name;

    do {
        name += 'A' + (index%26);
        index /= 26;
    } while (index);

    return name;
}

int main() {
#ifdef GENERATE_RANDOM_GRAPHS
    auto g = generate_random<subgraph<Graph> >();
#else
    auto g = create_data<subgraph<Graph> >();
#endif

    for (auto vd : make_iterator_range(vertices(g))) {
        put(get(vertex_attribute, g), vd, 
                GraphvizAttributes{
                    {"label", name_for_index(vd)}
                });
    }

    write_graphviz(std::cout, g);
}

关于c++ - 如何使用 boost::write_graphviz 编写 GraphViz 子图，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29312444/