Boost.Graph和Graphviz嵌套子图

Question

我需要验证码

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

using namespace boost;

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

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

int main()
{
    char names[] = {"AB"};
    enum {A, B, N};

    subgraph<graph_t> main(N);
    subgraph<graph_t>& sub1 = main.create_subgraph();
    subgraph<graph_t>& sub2 = sub1.create_subgraph();

    add_vertex(A, sub1);
    add_vertex(B, sub2);
    add_edge(A, B, main);

    get_property(main, graph_name) = "G0";
    get_property(sub1, graph_name) = "clusterG1";
    get_property(sub2, graph_name) = "clusterG2";

    write_graphviz(std::cout, main, make_iterator_vertex_map(names));
}

生成左侧的图形，而我得到右侧的图形：

输出为：

digraph G0 {
subgraph clusterG1 {
subgraph clusterG2 {
//B;
}
//A;
}
A -> B;
}

带注释的节点语句是丢失层次结构信息的地方（我的输出中没有这些行）。如何避免这种情况？

---

如果我将两个顶点都添加到同一子图中：

add_vertex(A, sub1);
add_vertex(B, sub1);
add_edge(A, B, main);

连接A -> B出现在clusterG1的范围内，并且据我所知，在该处也将隐式声明所提到的顶点。

我正在使用Boost 1.68.0

Answer 1

好地方。 linked answer实际上具有UB，如您自己的答案所解释。传递给write_graphviz函数的映射实际上不应该具有graphviz输出的node_id。相反，该映射被假定为vertex_index_t属性映射。

[这可能是我从boost::print_graph（graph_utility.hpp）中得出的假设，[[确实

该属性映射。为了使其安全运行，我将修改示例以使用write_graphviz_dp-使用动态属性：

int main() {
    boost::dynamic_properties dp;
    dp.property("node_id", boost::make_transform_value_property_map<std::string>(&name_for_index, boost::identity_property_map{}));
    write_graphviz_dp(std::cout, create_data<subgraph<Graph> >(), dp);
}

我选择使用转换函数来获取任何顶点描述符的名称，也不想再假设任何关于顶点数目的东西，我编写了更通用的函数来生成诸如“ A”，...， Z”，“ AA”，...，“ ZZ”等：

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

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

    return name;
}

[Live On Coliru
] >>保留子图信息
以上重载没有子图支持。因此，让我们修复vertex_attribute贴图以具有预期的顶点标签：
int main() {
    auto g = create_data<subgraph<Graph> >();

    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);
}

现在可以打印：
[Live On Coliru] >>digraph G0 {
subgraph clusterG1 {
graph [
label=G1];
node [
color=red, shape=Mrecord];
0[label="Vertex A"];
1[label="Vertex B"];
0 -> 1;
}
subgraph clusterG2 {
graph [
fillcolor=lightgray, label=G2, style=filled];
node [
shape=circle];
4[label="Vertex E"];
2[label="Vertex C"];
5[label="Vertex F"];
4 -> 5;
2 -> 5;
}
3[label="Vertex D"];
1 -> 2;
1 -> 3;
4 -> 1;
5 -> 3;
}
哪个渲染为
完整列表
保留后代
#include <boost/graph/graphviz.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/subgraph.hpp>
#include <iostream>

using namespace boost;

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;
}

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 = "Vertex ";

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

    return name;
}

int main() {
    auto g = create_data<subgraph<Graph> >();

    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);
}

Answer 2

[故障是由于提供make_iterator_vertex_map(names)引起的，该char从names（'A'，'B'）返回vertex_index s。这与预期的（和默认的）0属性（1，

digraph G0 {
subgraph clusterG1 {
subgraph clusterG2 {
1;
}
0;
}
0 -> 1;
}

）不兼容。修复后，我得到：