修改Boost :: Graph中的顶点属性

Question

我试图找出如何使用boost :: graph来存储一些信息.但是,我希望有关于每个顶点的信息.盯着库的文档揭示了(a)写得不好的文档,或者(b),我显然不像我想的那样擅长C++.选择两个.

我正在寻找一个简单的示例用法.

Answer 1

使用捆绑属性怎么样？

using namespace boost;

struct vertex_info { 
    std::string whatever; 
    int othervalue; 
    std::vector<int> some_values; 
};

typedef adjacency_list<vecS, vecS, undirectedS, vertex_info> graph_t;

graph_t g(n);

g[0].whatever = "Vertex 0";

[...]

等等.

我经常使用BGL,使用捆绑属性非常简单(参见文档).

我经常使用的另一种顶点属性是外部属性.您可以声明std::vectors适当的大小,并在大多数时间和大多数算法中将它们用作属性.

Answer 2

我不喜欢boost :: graph的嵌套模板属性方法,因此我在所有内容周围编写了一个小包装器,它基本上允许将任何struct /类作为顶点/边属性.可以访问访问struct成员的属性.

为了保持灵活性,这些结构被定义为模板参数.

这里的代码:

/* definition of basic boost::graph properties */
enum vertex_properties_t { vertex_properties };
enum edge_properties_t { edge_properties };
namespace boost {
    BOOST_INSTALL_PROPERTY(vertex, properties);
    BOOST_INSTALL_PROPERTY(edge, properties);
}


/* the graph base class template */
template < typename VERTEXPROPERTIES, typename EDGEPROPERTIES >
class Graph
{
public:

    /* an adjacency_list like we need it */
    typedef adjacency_list<
        setS, // disallow parallel edges
        listS, // vertex container
        bidirectionalS, // directed graph
        property<vertex_properties_t, VERTEXPROPERTIES>,
        property<edge_properties_t, EDGEPROPERTIES>
    > GraphContainer;


    /* a bunch of graph-specific typedefs */
    typedef typename graph_traits<GraphContainer>::vertex_descriptor Vertex;
    typedef typename graph_traits<GraphContainer>::edge_descriptor Edge;
    typedef std::pair<Edge, Edge> EdgePair;

    typedef typename graph_traits<GraphContainer>::vertex_iterator vertex_iter;
    typedef typename graph_traits<GraphContainer>::edge_iterator edge_iter;
    typedef typename graph_traits<GraphContainer>::adjacency_iterator adjacency_iter;
    typedef typename graph_traits<GraphContainer>::out_edge_iterator out_edge_iter;

    typedef typename graph_traits<GraphContainer>::degree_size_type degree_t;

    typedef std::pair<adjacency_iter, adjacency_iter> adjacency_vertex_range_t;
    typedef std::pair<out_edge_iter, out_edge_iter> out_edge_range_t;
    typedef std::pair<vertex_iter, vertex_iter> vertex_range_t;
    typedef std::pair<edge_iter, edge_iter> edge_range_t;


    /* constructors etc. */
    Graph()
    {}

    Graph(const Graph& g) :
        graph(g.graph)
    {}

    virtual ~Graph()
    {}


    /* structure modification methods */
    void Clear()
    {
        graph.clear();
    }

    Vertex AddVertex(const VERTEXPROPERTIES& prop)
    {
        Vertex v = add_vertex(graph);
        properties(v) = prop;
        return v;
    }

    void RemoveVertex(const Vertex& v)
    {
        clear_vertex(v, graph);
        remove_vertex(v, graph);
    }

    EdgePair AddEdge(const Vertex& v1, const Vertex& v2, const EDGEPROPERTIES& prop_12, const EDGEPROPERTIES& prop_21)
    {
        /* TODO: maybe one wants to check if this edge could be inserted */
        Edge addedEdge1 = add_edge(v1, v2, graph).first;
        Edge addedEdge2 = add_edge(v2, v1, graph).first;

        properties(addedEdge1) = prop_12;
        properties(addedEdge2) = prop_21;

        return EdgePair(addedEdge1, addedEdge2);
    }


    /* property access */
    VERTEXPROPERTIES& properties(const Vertex& v)
    {
        typename property_map<GraphContainer, vertex_properties_t>::type param = get(vertex_properties, graph);
        return param[v];
    }

    const VERTEXPROPERTIES& properties(const Vertex& v) const
    {
        typename property_map<GraphContainer, vertex_properties_t>::const_type param = get(vertex_properties, graph);
        return param[v];
    }

    EDGEPROPERTIES& properties(const Edge& v)
    {
        typename property_map<GraphContainer, edge_properties_t>::type param = get(edge_properties, graph);
        return param[v];
    }

    const EDGEPROPERTIES& properties(const Edge& v) const
    {
        typename property_map<GraphContainer, edge_properties_t>::const_type param = get(edge_properties, graph);
        return param[v];
    }


    /* selectors and properties */
    const GraphContainer& getGraph() const
    {
        return graph;
    }

    vertex_range_t getVertices() const
    {
        return vertices(graph);
    }

    adjacency_vertex_range_t getAdjacentVertices(const Vertex& v) const
    {
        return adjacent_vertices(v, graph);
    }

    int getVertexCount() const
    {
        return num_vertices(graph);
    }

    int getVertexDegree(const Vertex& v) const
    {
        return out_degree(v, graph);
    }


    /* operators */
    Graph& operator=(const Graph &rhs)
    {
        graph = rhs.graph;
        return *this;
    }

protected:
    GraphContainer graph;
};

使用此功能,您可以访问以下属性:

struct VertexProperties {
    int i;
};

struct EdgeProperties {
};

typedef Graph<VertexProperties, EdgeProperties> MyGraph;

MyGraph g;

VertexProperties vp;
vp.i = 42;

MyGraph::Vertex v = g.AddVertex(vp);

g.properties(v).i = 23;

当然,您的图形结构可能还有其他需求,但上面代码的修改应该非常简单.

Answer 3

我认为 Boost.Graph 有一个非常好的文档，但并不真正适合初学者。这是一个我希望足够简单的例子！

//includes

// Create a name for your information
struct VertexInformation
{
  typedef boost::vertex_property_type type;
};

// Graph type, customize it to your needs
// This is when you decide what information will be attached to vertices and/or edges
// of MyGraph objects
typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS,
  boost::property<VertexInformation, double> > MyGraph;

int main()
{
  MyGraph graph;

  // Create accessor for information
  typedef boost::property_map<MyGraph, VertexInformation>::type  InformationAccessor;
  InformationAccessor information( get( VertexInformation(), graph ) );

  // Create a vertex (for example purpose)
  typedef boost::graph_traits<MyGraph>::vertex_descriptor MyVertex;
  MyVertex vertex = add_vertex( graph );

  // Now you can access your information
  put( information, vertex, 1. );

  // returns 1 !
  get( information, vertex );
  return 0;
}