orr_graph.h

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/*
 * orr_graph.h
 *
 *  Created on: Nov 23, 2012
 *      Author: papazov
 */
 
#pragma once
 
#include <algorithm>
#include <cstddef>
#include <list>
#include <set>
#include <vector>
 
namespace pcl
{
  namespace recognition
  {
    template<class NodeData>
    class ORRGraph
    {
      public:
        class Node
        {
          public:
            enum State {ON, OFF, UNDEF};
 
            Node (int id)
            : id_ (id),
              state_(UNDEF)
            {}
 
            virtual ~Node () = default;
 
            inline const std::set<Node*>&
            getNeighbors () const
            {
              return (neighbors_);
            }
 
            inline const NodeData&
            getData () const
            {
              return (data_);
            }
 
            inline void
            setData (const NodeData& data)
            {
              data_ = data;
            }
 
            inline int
            getId () const
            {
              return (id_);
            }
 
            inline void
            setId (int id)
            {
              id_ = id;
            }
 
            inline void
            setFitness (int fitness)
            {
              fitness_ = fitness;
            }
 
            static inline bool
            compare (const Node* a, const Node* b)
            {
              return a->fitness_ > b->fitness_;
            }
 
            friend class ORRGraph;
 
          protected:
            std::set<Node*> neighbors_;
            NodeData data_;
            int id_;
            int fitness_;
            State state_;
        };
 
      public:
        ORRGraph () = default;
        virtual ~ORRGraph (){ this->clear ();}
 
        inline void
        clear ()
        {
          for ( auto nit = nodes_.begin () ; nit != nodes_.end () ; ++nit )
            delete *nit;
 
          nodes_.clear ();
        }
 
        /** \brief Drops all existing graph nodes and creates 'n' new ones. */
        inline void
        resize (int n)
        {
          if ( !n )
            return;
 
          for ( auto nit = nodes_.begin () ; nit != nodes_.end () ; ++nit )
            delete *nit;
 
          nodes_.resize (static_cast<std::size_t> (n));
 
          for ( int i = 0 ; i < n ; ++i )
            nodes_[i] = new Node (i);
        }
 
        inline void
        computeMaximalOnOffPartition (std::list<Node*>& on_nodes, std::list<Node*>& off_nodes)
        {
          std::vector<Node*> sorted_nodes (nodes_.size ());
          int i = 0;
 
          // Set all nodes to undefined
          for ( auto it = nodes_.begin () ; it != nodes_.end () ; ++it )
          {
            sorted_nodes[i++] = *it;
            (*it)->state_ = Node::UNDEF;
          }
 
          // Now sort the nodes according to the fitness
          std::sort (sorted_nodes.begin (), sorted_nodes.end (), Node::compare);
 
          // Now run through the array and start switching nodes on and off
          for ( auto it = sorted_nodes.begin () ; it != sorted_nodes.end () ; ++it )
          {
            // Ignore graph nodes which are already OFF
            if ( (*it)->state_ == Node::OFF )
              continue;
 
            // Set the node to ON
            (*it)->state_ = Node::ON;
 
            // Set all its neighbors to OFF
            for ( auto neigh = (*it)->neighbors_.begin () ; neigh != (*it)->neighbors_.end () ; ++neigh )
            {
              (*neigh)->state_ = Node::OFF;
              off_nodes.push_back (*neigh);
            }
 
            // Output the node
            on_nodes.push_back (*it);
          }
        }
 
        inline void
        insertUndirectedEdge (int id1, int id2)
        {
          nodes_[id1]->neighbors_.insert (nodes_[id2]);
          nodes_[id2]->neighbors_.insert (nodes_[id1]);
        }
 
        inline void
        insertDirectedEdge (int id1, int id2)
        {
          nodes_[id1]->neighbors_.insert (nodes_[id2]);
        }
 
        inline void
        deleteUndirectedEdge (int id1, int id2)
        {
          nodes_[id1]->neighbors_.erase (nodes_[id2]);
          nodes_[id2]->neighbors_.erase (nodes_[id1]);
        }
 
        inline void
        deleteDirectedEdge (int id1, int id2)
        {
          nodes_[id1]->neighbors_.erase (nodes_[id2]);
        }
 
        inline typename std::vector<Node*>&
        getNodes (){ return nodes_;}
 
      public:
        typename std::vector<Node*> nodes_;
    };
  } // namespace recognition
} // namespace pcl