NICE_VisLearning/math/cluster/RandomClustering.h

/** 
* @file RandomClustering.h
* @brief Clustering by randomly picking some samples from the set of features as representatives
* @author Alexander Freytag
* @date 03-06-2013 (dd-mm-yyyy)
*/
#ifndef RANDOMCLUSTERERNINCLUDE
#define RANDOMCLUSTERERNINCLUDE

#include <core/basics/Config.h>
#include <core/vector/Distance.h>
#include <core/vector/MatrixT.h>
#include <core/vector/VectorT.h>
  
#include "ClusterAlgorithm.h"

namespace OBJREC {

  /**
   * @class RandomClustering
   * @brief Clustering by randomly picking some samples from the set of features as representatives
   * @author Alexander Freytag
   * @date 03-06-2013 (dd-mm-yyyy)
  */    
  class RandomClustering : public ClusterAlgorithm
  {

      protected:
        
      /************************
       * 
       *   protected variables
       * 
       **************************/ 
      
        //! desired number of clusters
        int noClusters;
        
        //! specify which distance to use for calculating assignments
        std::string distanceType;
        
        //! the actual distance metric
        NICE::VectorDistance<double> *distancefunction;        
        
  
       /************************
       * 
       *   protected methods
       * 
       **************************/  
      
        
        //! compute assignments of all given features wrt to the currently known prototypes (cluster medoids) == ~ E-step
        double compute_assignments ( const NICE::VVector & features,
                  const NICE::VVector & prototypes,
                  std::vector<int> & assignment );

        //! compute number of assignments for every currently found cluster
        double compute_weights ( const NICE::VVector & features,
              std::vector<double> & weights,
              std::vector<int>    & assignment );


        //! compute (update) prototypes given the current assignments == ~ M-step
        int compute_prototypes ( const NICE::VVector & features,
                NICE::VVector & prototypes,
                std::vector<double> & weights,
                const std::vector<int>    & assignment );

      public:
    
        /**
        * @brief simple constructor
        * @param _noClasses the number of clusters to be computed
        * @param _distanceMode a string specifying the distance function to be used (default: euclidean)* 
        * @date 03-06-2013 (dd-mm-yyyy)
        */
        RandomClustering( const int & _noClasses , const std::string & _distanceMode="euclidean" );
        
        /**
        * @brief standard constructor
        * @param conf config file specifying all relevant variable settings
        * @param _section name of the section within the configfile where the settings can be found (default: RandomClustering)
        * @date 03-06-2013 (dd-mm-yyyy)
        */
        RandomClustering( const NICE::Config *conf, const std::string & _section = "RandomClustering");

        
            
        /** simple destructor */
        virtual ~RandomClustering();
          
        /**
        * @brief this is the actual method that performs the clustering for a given set of features
        * @author Alexander Freytag
        * @date 03-06-2013 (dd-mm-yyyy)
        * @param   features input features to be clustered
        * @param   prototypes computed prototypes (randomly chosen) for the given samples
        * @param   weights number of assignments for every cluster
        * @param   assignment explicite assignments of features to computed cluster medoids
        */        
        void cluster ( const NICE::VVector & features,
                NICE::VVector & prototypes,
                std::vector<double> & weights,
                std::vector<int>    & assignment );

  };


} // namespace

#endif