c++ - 使用带有笛卡尔点的 boost 连接组件

Question

我找到了 http://www.boost.org/doc/libs/1_49_0/libs/graph/example/incremental_components.cpp并想检查它是否适合我。如何转换此示例以处理具有 (x,y) 或 (x,y,z) 的笛卡尔点。我在 boost 的文档中找不到这样的例子。

我发现我必须以某种方式重新定义顶点，因此需要更改 adjacency_list。尝试用 Point 定义更改 vecS，但我认为还需要对 add_edge 函数进行一些更改。

Answer 1

我也对您指出的示例进行了一些小改动。具体将 adjacency_list 上的第四和第五个模板参数设置为包含任何其他顶点和边属性的类型。请在此处查看文档:http://www.boost.org/doc/libs/1_48_0/libs/graph/doc/adjacency_list.html

struct point
{
 int x;
 int y;
 int z;
};

typedef adjacency_list <vecS, vecS, undirectedS, point > Graph;

在节点和顶点之后，可以像这样设置附加点数据:

graph[0].x = 42;

并在计算完组件后在最后检索:

std::cout << child_index << " " << "x=" << graph[current_index].x << " ";

完整代码:

//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Copyright 2009 Trustees of Indiana University.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek, Michael Hansen
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
#include <iostream>
#include <vector>

#include <boost/foreach.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/graph_utility.hpp>
#include <boost/graph/incremental_components.hpp>
#include <boost/pending/disjoint_sets.hpp>

/*

  This example shows how to use the disjoint set data structure
  to compute the connected components of an undirected, changing
  graph.

  Sample output:

  An undirected graph:
  0 <--> 1 4 
  1 <--> 0 4 
  2 <--> 5 
  3 <--> 
  4 <--> 1 0 
  5 <--> 2 

  representative[0] = 1
  representative[1] = 1
  representative[2] = 5
  representative[3] = 3
  representative[4] = 1
  representative[5] = 5

  component 0 contains: 4 1 0 
  component 1 contains: 3 
  component 2 contains: 5 2 

 */

using namespace boost;

struct point
{
  point() : x(0), y(0), z(0) {}
  int x;
  int y;
  int z;
};

int main(int argc, char* argv[]) 
{
  typedef adjacency_list <vecS, vecS, undirectedS, point > Graph;
  typedef graph_traits<Graph>::vertex_descriptor Vertex;
  typedef graph_traits<Graph>::vertices_size_type VertexIndex;

  const int VERTEX_COUNT = 6;
  Graph graph(VERTEX_COUNT);

  std::vector<VertexIndex> rank(num_vertices(graph));
  std::vector<Vertex> parent(num_vertices(graph));

  typedef VertexIndex* Rank;
  typedef Vertex* Parent;

  disjoint_sets<Rank, Parent> ds(&rank[0], &parent[0]);

  initialize_incremental_components(graph, ds);
  incremental_components(graph, ds);

  graph_traits<Graph>::edge_descriptor edge;
  bool flag;

  boost::tie(edge, flag) = add_edge(0, 1, graph);
  ds.union_set(0,1);

  boost::tie(edge, flag) = add_edge(1, 4, graph);
  ds.union_set(1,4);

  boost::tie(edge, flag) = add_edge(4, 0, graph);
  ds.union_set(4,0);

  boost::tie(edge, flag) = add_edge(2, 5, graph);
  ds.union_set(2,5);

  graph[0].x = 42;

  std::cout << "An undirected graph:" << std::endl;
  print_graph(graph, get(boost::vertex_index, graph));
  std::cout << std::endl;

  BOOST_FOREACH(Vertex current_vertex, vertices(graph)) {
    std::cout << "representative[" << current_vertex << "] = " <<
      ds.find_set(current_vertex) << std::endl;
  }

  std::cout << std::endl;

  typedef component_index<VertexIndex> Components;

  // NOTE: Because we're using vecS for the graph type, we're
  // effectively using identity_property_map for a vertex index map.
  // If we were to use listS instead, the index map would need to be
  // explicitly passed to the component_index constructor.
  Components components(parent.begin(), parent.end());

  // Iterate through the component indices
  BOOST_FOREACH(VertexIndex current_index, components) {
    std::cout << "component " << current_index << " contains: ";

    // Iterate through the child vertex indices for [current_index]
    BOOST_FOREACH(VertexIndex child_index,
                  components[current_index]) 
    {
      std::cout << child_index 
                << " {" << graph[child_index].x
                 << "," << graph[child_index].y
                 << "," << graph[child_index].z << "} ";
    }

    std::cout << std::endl;
  }

  return (0);
}