Example #1
0
// Solve the maze using A-star search.  Return true if a solution was found.
bool maze::solve() {
  boost::static_property_map<distance> weight(1);
  // The predecessor map is a vertex-to-vertex mapping.
  typedef boost::unordered_map<vertex_descriptor,
                               vertex_descriptor,
                               vertex_hash> pred_map;
  pred_map predecessor;
  boost::associative_property_map<pred_map> pred_pmap(predecessor);
  // The distance map is a vertex-to-distance mapping.
  typedef boost::unordered_map<vertex_descriptor,
                               distance,
                               vertex_hash> dist_map;
  dist_map distance;
  boost::associative_property_map<dist_map> dist_pmap(distance);

  vertex_descriptor s = source();
  vertex_descriptor g = goal();
  euclidean_heuristic heuristic(g);
  astar_goal_visitor visitor(g);

  try {
    astar_search(m_barrier_grid, s, heuristic,
                 boost::weight_map(weight).
                 predecessor_map(pred_pmap).
                 distance_map(dist_pmap).
                 visitor(visitor) );
  } catch(found_goal fg) {
    // Walk backwards from the goal through the predecessor chain adding
    // vertices to the solution path.
    for (vertex_descriptor u = g; u != s; u = predecessor[u])
      m_solution.insert(u);
    m_solution.insert(s);
    m_solution_length = distance[g];
    return true;
  }

  return false;
}
Example #2
0
  OutputIterator
  sloan_ordering(Graph& g,
                 typename graph_traits<Graph>::vertex_descriptor s,
                 typename graph_traits<Graph>::vertex_descriptor e,
                 OutputIterator permutation, 
                 ColorMap color, 
                 DegreeMap degree, 
                 PriorityMap priority, 
                 Weight W1, 
                 Weight W2)
  {
    //typedef typename property_traits<DegreeMap>::value_type Degree;
    typedef typename property_traits<PriorityMap>::value_type Degree;
    typedef typename property_traits<ColorMap>::value_type ColorValue;
    typedef color_traits<ColorValue> Color;
    typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
    typedef typename std::vector<typename graph_traits<Graph>::vertices_size_type>::iterator vec_iter;
    typedef typename graph_traits<Graph>::vertices_size_type size_type;

    typedef typename property_map<Graph, vertex_index_t>::const_type VertexID;

    
    //Creating a std-vector for storing the distance from the end vertex in it
    typename std::vector<typename graph_traits<Graph>::vertices_size_type> dist(num_vertices(g), 0);
    
    //Wrap a property_map_iterator around the std::iterator
    boost::iterator_property_map<vec_iter, VertexID, size_type, size_type&> dist_pmap(dist.begin(), get(vertex_index, g)); 
    
    breadth_first_search
      (g, e, visitor
       (
           make_bfs_visitor(record_distances(dist_pmap, on_tree_edge() ) )
        )
       );
    
    //Creating a property_map for the indices of a vertex
    typename property_map<Graph, vertex_index_t>::type index_map = get(vertex_index, g);
    
    //Sets the color and priority to their initial status
    unsigned cdeg;    
    typename graph_traits<Graph>::vertex_iterator ui, ui_end;
    for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui)
    {
        put(color, *ui, Color::white());
        cdeg=get(degree, *ui)+1;
        put(priority, *ui, W1*dist[index_map[*ui]]-W2*cdeg );  
    }
    
    //Priority list
    typedef indirect_cmp<PriorityMap, std::greater<Degree> > Compare;
    Compare comp(priority);
    std::list<Vertex> priority_list;

    //Some more declarations
    typename graph_traits<Graph>::out_edge_iterator ei, ei_end, ei2, ei2_end;
    Vertex u, v, w;

    put(color, s, Color::green());      //Sets the color of the starting vertex to gray
    priority_list.push_front(s);                 //Puts s into the priority_list
    
    while ( !priority_list.empty() ) 
    {  
      priority_list.sort(comp);         //Orders the elements in the priority list in an ascending manner
      
      u = priority_list.front();           //Accesses the last element in the priority list
      priority_list.pop_front();               //Removes the last element in the priority list
      
      if(get(color, u) == Color::green() )
      {
        //for-loop over all out-edges of vertex u
        for (boost::tie(ei, ei_end) = out_edges(u, g); ei != ei_end; ++ei) 
        {
          v = target(*ei, g);
          
          put( priority, v, get(priority, v) + W2 ); //updates the priority
          
          if (get(color, v) == Color::white() )      //test if the vertex is inactive
          {
            put(color, v, Color::green() );        //giving the vertex a preactive status
            priority_list.push_front(v);                     //writing the vertex in the priority_queue
          }           
        }
      }
      
      //Here starts step 8
      *permutation++ = u;                      //Puts u to the first position in the permutation-vector
      put(color, u, Color::black() );          //Gives u an inactive status
      
      //for loop over all the adjacent vertices of u
      for (boost::tie(ei, ei_end) = out_edges(u, g); ei != ei_end; ++ei) {
        
        v = target(*ei, g);     
        
        if (get(color, v) == Color::green() ) {      //tests if the vertex is inactive
          
          put(color, v, Color::red() );        //giving the vertex an active status
          put(priority, v, get(priority, v)+W2);  //updates the priority        
          
          //for loop over alll adjacent vertices of v
          for (boost::tie(ei2, ei2_end) = out_edges(v, g); ei2 != ei2_end; ++ei2) {
            w = target(*ei2, g);
            
            if(get(color, w) != Color::black() ) {     //tests if vertex is postactive
              
              put(priority, w, get(priority, w)+W2);  //updates the priority
              
              if(get(color, w) == Color::white() ){
                
                put(color, w, Color::green() );   // gives the vertex a preactive status
                priority_list.push_front(w);           // puts the vertex into the priority queue
                
              } //end if
              
            } //end if
            
          } //end for
          
        } //end if
        
      } //end for
      
    } //end while
    
    
    return permutation;
  }  
Example #3
0
  typename graph_traits<Graph>::vertex_descriptor 
  sloan_start_end_vertices(Graph& G, 
                           typename graph_traits<Graph>::vertex_descriptor &s, 
                           ColorMap color, 
                           DegreeMap degree)
  {
    typedef typename property_traits<DegreeMap>::value_type Degree;
    typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
    typedef typename std::vector< typename graph_traits<Graph>::vertices_size_type>::iterator vec_iter;
    typedef typename graph_traits<Graph>::vertices_size_type size_type;
    
    typedef typename property_map<Graph, vertex_index_t>::const_type VertexID;
    
    s = *(vertices(G).first);
    Vertex e = s;
    Vertex i;
    unsigned my_degree = get(degree, s ); 
    unsigned dummy, h_i, h_s, w_i, w_e;
    bool new_start = true;
    unsigned maximum_degree = 0;
    
    //Creating a std-vector for storing the distance from the start vertex in dist
    std::vector<typename graph_traits<Graph>::vertices_size_type> dist(num_vertices(G), 0);

    //Wrap a property_map_iterator around the std::iterator
    boost::iterator_property_map<vec_iter, VertexID, size_type, size_type&> dist_pmap(dist.begin(), get(vertex_index, G));
    
    //Creating a property_map for the indices of a vertex
    typename property_map<Graph, vertex_index_t>::type index_map = get(vertex_index, G);
    
    //Creating a priority queue
    typedef indirect_cmp<DegreeMap, std::greater<Degree> > Compare;
    Compare comp(degree);
    std::priority_queue<Vertex, std::vector<Vertex>, Compare> degree_queue(comp);
    
    //step 1
    //Scan for the vertex with the smallest degree and the maximum degree
    typename graph_traits<Graph>::vertex_iterator ui, ui_end;
    for (boost::tie(ui, ui_end) = vertices(G); ui != ui_end; ++ui)
    {
      dummy = get(degree, *ui);
      
      if(dummy < my_degree)
      {
        my_degree = dummy;
        s = *ui;
      }
      
      if(dummy > maximum_degree)
      {
        maximum_degree = dummy;
      }
    }
    //end 1
    
    do{  
      new_start = false;     //Setting the loop repetition status to false
      
      //step 2
      //initialize the the disance std-vector with 0
      for(typename std::vector<typename graph_traits<Graph>::vertices_size_type>::iterator iter = dist.begin(); iter != dist.end(); ++iter) *iter = 0;
      
      //generating the RLS (rooted level structure)
      breadth_first_search
        (G, s, visitor
         (
           make_bfs_visitor(record_distances(dist_pmap, on_tree_edge() ) )
           )
          );
      
      //end 2
      
      //step 3
      //calculating the depth of the RLS
      h_s = RLS_depth(dist);
      
      //step 4
      //pushing one node of each degree in an ascending manner into degree_queue
      std::vector<bool> shrink_trace(maximum_degree, false);
      for (boost::tie(ui, ui_end) = vertices(G); ui != ui_end; ++ui)
      {
        dummy = get(degree, *ui);
        
        if( (dist[index_map[*ui]] == h_s ) && ( !shrink_trace[ dummy ] ) )
        {
          degree_queue.push(*ui);
          shrink_trace[ dummy ] = true;
        }
      }
      
      //end 3 & 4

      
      // step 5
      // Initializing w
      w_e = (std::numeric_limits<unsigned>::max)();
      //end 5
      
      
      //step 6
      //Testing for termination
      while( !degree_queue.empty() )
      {
        i = degree_queue.top();       //getting the node with the lowest degree from the degree queue
        degree_queue.pop();           //ereasing the node with the lowest degree from the degree queue
        
        //generating a RLS          
        for(typename std::vector<typename graph_traits<Graph>::vertices_size_type>::iterator iter = dist.begin(); iter != dist.end(); ++iter) *iter = 0;
        
        breadth_first_search
          (G, i, boost::visitor
           (
             make_bfs_visitor(record_distances(dist_pmap, on_tree_edge() ) )
             )
            );
        
        //Calculating depth and width of the rooted level
        h_i = RLS_depth(dist);
        w_i = RLS_max_width(dist, h_i);
        
        //Testing for termination
        if( (h_i > h_s) && (w_i < w_e) ) 
        {
          h_s = h_i;
          s = i;
          while(!degree_queue.empty()) degree_queue.pop();
          new_start = true;         
        }
        else if(w_i < w_e)
        { 
          w_e = w_i;
          e = i;
        }
      }
      //end 6
        
    }while(new_start);
    
    return e;
  }