Question

我使用带有自定义类的增强有向图作为顶点的捆绑属性，并希望使用graphviz以DOT格式打印它。该类有一个私有变量，其值我想出现在DOT文件中。

演示我的问题的示例代码：

#include <iostream>
#include <boost/graph/directed_graph.hpp>
#include <boost/graph/graphviz.hpp>
#include <boost/property_map/transform_value_property_map.hpp>

class VertexClass
{
public:
    VertexClass() { id = 12; }
    VertexClass( int newId ) { id = newId; }
    int get_id() { return id; }
    void set_id( int newId ) { id = newId; }
private:
    int id;
};

typedef boost::directed_graph<VertexClass, boost::no_property> Graph;

int main(int,char*[])
{
    Graph g;

    Graph::vertex_descriptor v0 = g.add_vertex(3);
    Graph::vertex_descriptor v1 = g.add_vertex(5);
    Graph::vertex_descriptor v2 = g.add_vertex(6);

    boost::add_edge(v0,v1,g);
    boost::add_edge(v1,v2,g);

    //boost::write_graphviz(std::cout, g, ...);

    return 0;
}

期望的输出：

digraph G {
0[label=3];
1[label=5];
2[label=6];
0->1 ;
1->2 ;
}

（通过将“id”公开并在代码下面运行获得。）

现在，“id”是私有的，所以在代码下面（我发现阅读其他类似的问题）对我不起作用：

boost::write_graphviz(std::cout, g, boost::make_label_writer(boost::get(&VertexClass::id, g)));

我想我必须使用访问器来获取id。经过一些搜索，我发现有人建议使用值转换属性映射（make_transform_value_property_map）。

然后我找到了this answer。但问题是，在这种情况下，属性未定义为捆绑，而是使用枚举和BOOST_INSTALL_PROPERTY。因为我没有这个方法提供的这些标签（并且我很难切换方法，因为我的实际代码更复杂），它对我不起作用（或者至少我不知道如何做到这一点）。

接下来，在阅读this answer后，我尝试了以下内容：

boost::write_graphviz(std::cout, g, boost::make_label_writer(boost::make_transform_value_property_map(&VertexClass::get_id, boost::get(boost::vertex_bundle, g))));

但是我收到以下错误（下面的完整输出）：

$ g++ -Wall -std=c++11 main.cpp
In file included from /usr/local/include/boost/graph/directed_graph.hpp:13:0,
                 from main.cpp:2:
/usr/local/include/boost/property_map/transform_value_property_map.hpp: In instantiation of ‘boost::transform_value_property_map<Func, PM, Ret>::reference boost::transform_value_property_map<Func, PM, Ret>::operator[](const key_type&) const [with Func = int (VertexClass::*)(); PM = boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>; Ret = int; boost::transform_value_property_map<Func, PM, Ret>::reference = int; boost::transform_value_property_map<Func, PM, Ret>::key_type = void*]’:
/usr/local/include/boost/property_map/property_map.hpp:303:54:   required from ‘Reference boost::get(const boost::put_get_helper<Reference, PropertyMap>&, const K&) [with PropertyMap = boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int>; Reference = int; K = void*]’
/usr/local/include/boost/graph/graphviz.hpp:85:56:   required from ‘void boost::label_writer<Name>::operator()(std::ostream&, const VertexOrEdge&) const [with VertexOrEdge = void*; Name = boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int>; std::ostream = std::basic_ostream<char>]’
/usr/local/include/boost/graph/graphviz.hpp:270:18:   required from ‘void boost::write_graphviz(std::ostream&, const Graph&, VertexPropertiesWriter, EdgePropertiesWriter, GraphPropertiesWriter, VertexID, typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<Graph>::traversal_category>::value, boost::graph::detail::no_parameter>::type) [with Graph = boost::directed_graph<VertexClass, boost::no_property>; VertexPropertiesWriter = boost::label_writer<boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int> >; EdgePropertiesWriter = boost::default_writer; GraphPropertiesWriter = boost::default_writer; VertexID = boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, unsigned int, const unsigned int&, boost::vertex_index_t>; std::ostream = std::basic_ostream<char>; typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<Graph>::traversal_category>::value, boost::graph::detail::no_parameter>::type = boost::graph::detail::no_parameter]’
/usr/local/include/boost/graph/graphviz.hpp:290:63:   required from ‘void boost::write_graphviz(std::ostream&, const Graph&, VertexPropertiesWriter, EdgePropertiesWriter, GraphPropertiesWriter, typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<Graph>::traversal_category>::value, boost::graph::detail::no_parameter>::type) [with Graph = boost::directed_graph<VertexClass, boost::no_property>; VertexPropertiesWriter = boost::label_writer<boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int> >; EdgePropertiesWriter = boost::default_writer; GraphPropertiesWriter = boost::default_writer; std::ostream = std::basic_ostream<char>; typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<Graph>::traversal_category>::value, boost::graph::detail::no_parameter>::type = boost::graph::detail::no_parameter]’
/usr/local/include/boost/graph/graphviz.hpp:309:38:   required from ‘void boost::write_graphviz(std::ostream&, const Graph&, VertexWriter, typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<Graph>::traversal_category>::value, boost::graph::detail::no_parameter>::type) [with Graph = boost::directed_graph<VertexClass, boost::no_property>; VertexWriter = boost::label_writer<boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int> >; std::ostream = std::basic_ostream<char>; typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<Graph>::traversal_category>::value, boost::graph::detail::no_parameter>::type = boost::graph::detail::no_parameter]’
main.cpp:30:166:   required from here
/usr/local/include/boost/property_map/transform_value_property_map.hpp:45:24: error: must use ‘.*’ or ‘->*’ to call pointer-to-member function in ‘((const boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int>*)this)->boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int>::f (...)’, e.g. ‘(... ->* ((const boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int>*)this)->boost::transform_value_property_map<int (VertexClass::*)(), boost::adj_list_vertex_property_map<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, VertexClass>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>, VertexClass, VertexClass&, boost::vertex_bundle_t>, int>::f) (...)’
     return f(get(pm, k));

我看到的每个问题/答案都是关于上述两种情况中的一种（带有公共变量的捆绑属性（例如结构）或老式属性声明）。

我是boost图库中的新手，所以我想我可能错过了一些东西。但我无法找到解决方案（并且在boost的文档中真的丢失了），所以任何帮助都会非常感激。

Answer 1

transform_value_property_map的附加内容向我表明您已接近解决方案。这是：

boost::dynamic_properties dp;

首先，让我们说明你想要graphviz节点id的内在顶点索引：

dp.property("node_id", get(boost::vertex_index, g));

现在我们想要使用捆绑包做一些事情，所以让我们抓住整个捆绑包的属性映射：

auto vbundle = get(boost::vertex_bundle, g);

但我们无法直接使用它。我们需要改变它：

dp.property("label", 
        boost::make_transform_value_property_map([](VertexClass const& vd) {
            return vd.get_id();
            }, vbundle));

请注意！我已使get_id() const不变以进行此编译

现在写：

boost::write_graphviz_dp(std::cout, g, dp);

结果：

<强> Live On Coliru

digraph G {
0 [label=3];
1 [label=5];
2 [label=6];
0->1 ;
1->2 ;
}

备选方案＃1

在这种情况下，可以更简单地逃脱：

<强> Live On Coliru

dp.property("label", 
    boost::make_transform_value_property_map(std::mem_fn(&VertexClass::get_id), vbundle));

而是更灵活的lambda

备选方案＃2：没有准类

你似乎陷入了要求准类（PDF）的陷阱，他们没有增加任何价值。简化：

<强> Live On Coliru

#include <boost/graph/directed_graph.hpp>
#include <boost/graph/graphviz.hpp>
#include <iostream>

struct VertexProps { int id; };
typedef boost::directed_graph<VertexProps> Graph;

int main() {
    Graph g;
    auto v1 = add_vertex({5}, g);

    add_edge(add_vertex({3}, g), v1, g);
    add_edge(v1, add_vertex({6}, g), g);

    boost::dynamic_properties dp;
    dp.property("node_id", get(boost::vertex_index, g));
    dp.property("label", get(&VertexProps::id, g));

    write_graphviz_dp(std::cout, g, dp);
}

正如您现在所看到的，整个事物缩小到20行代码，并为您的顶点属性提供一流的支持。

输出（对于GraphViz）使用其属性提升图形顶点，使用带有私有变量的类作为捆绑属性

1 个答案:

备选方案＃1

备选方案＃2：没有准类