c++ - 使用 boost 库从文件创建图形

Question

我正在尝试编写一个程序，该程序可以使用 BOOST 库从文件中读取和创建图形。首先，我从一些解释开始。该文件类似于:http://pastebin.com/g4cgaHJB每次我找到像 (t # 1) 这样的线时，它的均值图的 id 为 1。(v 0 12) 它的平均顶点 ID 为 0，标签为 12。(e 1 3 52) 它在 id 为 1 的顶点和 id 为 3 的顶点之间带有标签 52 的平均边。

我从读取文件开始，每次找到 (t # ..) 我都会创建一个图形并将其放入图形 vector 中。这是代码:

#include <iostream>
#include <vector>
#include <ctime>
#include <set>
#include <fstream>
#include <string>
#include <unordered_set>
#include <cstdlib>
#include <boost/algorithm/string/split.hpp>
#include <boost/algorithm/string/classification.hpp>
#include <boost/graph/adjacency_list.hpp>
using namespace std;
using namespace boost;
using namespace boost::algorithm;



/*********************************************/
//vertex
struct VertexProperties
{
    int id;
    int label;

    VertexProperties(){}
    VertexProperties(unsigned i, unsigned l) : id(i), label(l) {}
};

//edge
struct EdgeProperties
{
    unsigned id;
    unsigned label;
    EdgeProperties(){}
    EdgeProperties(unsigned i, unsigned l) : id(i), label(l) {}
};

//Graph
struct GraphProperties
{
    unsigned id;
    unsigned label;
    GraphProperties()  {}
    GraphProperties(unsigned i, unsigned l) : id(i), label(l) {}
};


//adjency list
typedef boost::adjacency_list<
    boost::vecS, boost::vecS, boost::directedS,
    VertexProperties,
    EdgeProperties,
    GraphProperties
> Graph;


//descriptors
typedef boost::graph_traits<Graph>::vertex_descriptor vertex_t;
typedef std::pair<boost::graph_traits<Graph>::edge_descriptor, bool> edge_t;
//iterators
typedef graph_traits<Graph>::vertex_iterator vertex_iter;
typedef graph_traits<Graph>::edge_iterator edge_iter;
/****************************************************************************/
//le seuil int seuil;
std::vector<std::string> tokens;

/*
    programme principal
*/
int main()
{


    vector<Graph> dataG;  // vector<graphes> * pointsdataG;

    ifstream * file_reader= new ifstream("5.txt" ); //flux d'entrée pour opérer sur les fichiers.

    while (!file_reader->eof())
    {
        string line;

        file_reader->sync(); //Synchronise le tampon d'entree avec la source de donnees associee.

        getline(*file_reader, line); //lire les caracteres a partir du flux d'entree (file_reader) et les place dans une chaine: (line)
        if(line[0]=='t')  // ligne de transaction(graphe)
        {

            split(tokens, line, is_any_of(" "));
            int gid=atoi(tokens[2].c_str());
            Graph g(GraphProperties(gid,gid));


            cout<<gid<<endl;
            dataG.push_back(g);
        }
}
        std::cout << "dataG contains:";
        for (std::vector<Graph>::iterator it = dataG.begin() ; it != dataG.end(); ++it)
        {
            std::cout << ' ' << (*it)->label;
            std::cout << '\n';
        }
}

但是我对这条线有问题

std::cout << ' ' << (*it)->id;

解决这个问题后我会在每次前进时放上代码:)

Answer 1

首先，您的 myvector未在任何地方定义或声明。

其次，你说你对 std::cout << ' ' << (*it)->id; 有问题的行，在您的代码中不存在。

但是，问题很可能与您在代码中所做 的实际问题相同。您正在遍历包含 adjacency_list 的 vector 项，然后尝试从图形对象中提取节点值。

您需要一个额外的内部循环，以从节点中提取值。

---

更新1这可能是这样的:

  std::cout << "dataG contains:";
  for (auto gr : dataG)
  {
    for (size_t i = 0 ; i < num_vertices(gr) ; ++i) {
      std::cout << ' ' << gr[i].id << std::endl;
    }
  }

---

更新2

你的评论让我很困惑。如果您想做的是填充 adjacency_list，那么您可以这样做:

  while (!file_reader->eof())
  {
    string line;

    file_reader->sync();

    getline(*file_reader, line);
    std::stringstream ss(line);
    char lineType;
    ss >> lineType;
    if(lineType =='t')
    {
      char dummy;
      int gid;
      ss >> dummy >> gid;
      Graph g(GraphProperties(gid,gid));
      dataG.push_back(g);
    }  else if (lineType == 'v') {
      assert(!dataG.empty());
      int vId, vLabel;
      ss >> vId >> vLabel;
      boost::add_vertex(VertexProperties(vId, vLabel), dataG[dataG.size()-1]);
    } else if (lineType == 'e') {
      assert(!dataG.empty());
      int fromId, toId, vLabel;
      ss >> fromId >> toId >> vLabel;

      // Note that the EdgeProperty.id doesn't make sense with your input data
      // as it only contains [vertexFrom vertexTo edgeData]
      boost::add_edge(fromId, toId,
                      EdgeProperties(0, vLabel), dataG[dataG.size()-1]);
    }
  }

我相信您对“id”的使用对于顶点来说是多余的，因为它们都会附加隐式 id。但是，如果您仍然希望将其作为顶点属性，那很好。但是，您对边执行相同的操作，但边条目数据没有“id”字段。

---

更新3*

访问和输出图形的内容:

  typedef std::pair<edge_iter, edge_iter> edge_pair;
  std::cout << "dataG contains:" << std::endl;
  int c = 0;
  for (auto gr : dataG)
  {
    ++c;
    std::cout << "Graph " << c << " contains " << num_vertices(gr) << " vertices, and " << num_edges(gr) << " edges" << std::endl;
    std::cout << "  Vertex list: " << std::endl;
    for (size_t i = 0 ; i < num_vertices(gr) ; ++i) {
      std::cout << "    [" << i << "]   ID: " << gr[i].id << ", Label: " << gr[i].label << std::endl;
    }

    std::cout << "  Edge list: " << std::endl;
    edge_pair ep;
    for (ep = edges(gr); ep.first != ep.second; ++ep.first) {
      vertex_t from = source(*ep.first, gr);
      vertex_t to = target(*ep.first, gr);
      edge_t edg = edge(from, to, gr);
      std::cout << "    [" << gr[from].id << "," << gr[to].id << "]   ID: N/A,  Label: " <<  gr[edg.first].label << std::endl;
    }
    std::cout << std::endl;
  }

使用“5.txt”输出:

dataG contains:
Graph 1 contains 3 vertices, and 3 edges
  Vertex list: 
    [0]   ID: 0, Label: 0
    [1]   ID: 1, Label: 3
    [2]   ID: 2, Label: 9
  Edge list: 
    [0,1]   ID: N/A,  Label: 10
    [0,2]   ID: N/A,  Label: 4
    [2,1]   ID: N/A,  Label: 68

Graph 2 contains 6 vertices, and 3 edges
  Vertex list: 
    [0]   ID: 0, Label: 2
    [1]   ID: 1, Label: 11
    [2]   ID: 2, Label: 6
    [3]   ID: 3, Label: 10
    [4]   ID: 4, Label: 18
    [5]   ID: 5, Label: 14
  Edge list: 
    [0,1]   ID: N/A,  Label: 15
    [1,3]   ID: N/A,  Label: 20
    [2,5]   ID: N/A,  Label: 19

Graph 3 contains 2 vertices, and 1 edges
  Vertex list: 
    [0]   ID: 0, Label: 6
    [1]   ID: 1, Label: 11
  Edge list: 
    [0,1]   ID: N/A,  Label: 13

Graph 4 contains 4 vertices, and 3 edges
  Vertex list: 
    [0]   ID: 0, Label: 2
    [1]   ID: 1, Label: 11
    [2]   ID: 2, Label: 19
    [3]   ID: 3, Label: 2
  Edge list: 
    [0,1]   ID: N/A,  Label: 15
    [0,3]   ID: N/A,  Label: 19
    [1,2]   ID: N/A,  Label: 11

Graph 5 contains 3 vertices, and 4 edges
  Vertex list: 
    [0]   ID: 0, Label: 1
    [1]   ID: 1, Label: 16
    [2]   ID: 2, Label: 14
  Edge list: 
    [0,1]   ID: N/A,  Label: 8
    [0,2]   ID: N/A,  Label: 19
    [0,2]   ID: N/A,  Label: 19
    [1,2]   ID: N/A,  Label: 5