NICE_VisLearning/classifier/fpclassifier/boosting/FPCBoosting.h

/** 
* @file FPCBoosting.h
* @brief implementation of boosting algorithms
* @author Erik Rodner
* @date 04/24/2008

*/
#ifndef FPCBoostingINCLUDE
#define FPCBoostingINCLUDE

#include "core/vector/VectorT.h"
#include "core/vector/MatrixT.h"

#include "core/basics/Config.h"
#include "vislearning/classifier/classifierbase/FeaturePoolClassifier.h"
#include "vislearning/cbaselib/FeaturePool.h"
#include "core/basics/triplet.h"



namespace OBJREC {

/** @brief a strong classifier is a collection of weighted classifiers: \f$a \cdot h_t(\mathbf{x}) + b\f$ */
class StrongClassifier : public std::vector< triplet<double, double, FeaturePoolClassifier *> >
{};

/** @brief implementation of boosting algorithms */
class FPCBoosting : public FeaturePoolClassifier
{
    protected:
	const NICE::Config *conf;

	/** @brief normalize weights for each class independently */
	bool classwise_normalization;

	/** @brief boosting method ( select one value from the enum-type ) */
	int boosting_method;

	/** @brief class no corresponding to the positive class */
	int positive_class;

	/** @brief maximum number of rounds */
	int maxRounds;

	/** @brief memory efficiency by caching and storing of features on the hard disc */
	bool memory_efficient;

	/** @brief prototype of a weak classifier
	    
	    The generation of a new weak classifier is done by the clone method
	    of this object.
	*/
	FeaturePoolClassifier *weakClassifier;

	/** @brief final strong classifier */
	StrongClassifier strongClassifier;

	/** @brief perform boosting and build strongClassifier 
	    @param featureStorage pre calculated features
	    @param fp pool of features
	    @param examples training examples */
	void boosting ( const FeatureStorage & featureStorage,
			FeaturePool & fp,
			Examples & examples );

	/** @brief normalize weights of examples
	    @param examples training examples
	*/
	void normalizeWeights ( Examples & examples ) const;

    public:
	
	enum {
		BOOSTINGMETHOD_ADABOOST = 0,
		BOOSTINGMETHOD_REAL_ADABOOST,
		BOOSTINGMETHOD_GENTLEBOOST
	};

	/** @brief for cloning only */
	FPCBoosting() {};

	/** @brief constructor for training */
	FPCBoosting( const NICE::Config *conf, 
		  // refactor-nice.pl: check this substitution
		  // old: string section = "Boost" );
		  std::string section = "Boost" );
    
	/** @brief simple destructor */
	virtual ~FPCBoosting();

	/** @brief classify an unseen example */
	ClassificationResult classify ( Example & pce );
	
	/** @brief train this classifier 
	    @param fp pool of features
	    @param examples training examples
	*/
	virtual void train ( FeaturePool & fp,
		     Examples & examples );

	/** @{ methods for persistency */
	void restore (std::istream & is, int format = 0);
	void store (std::ostream & os, int format = 0) const;
	void clear ();
	/** @} */

	/** @brief creates a copy of this object */
	FeaturePoolClassifier *clone () const;

	/** @brief direct access to the classifier parameters */
	StrongClassifier & getStrongClassifier () { return strongClassifier; };

	/** @brief sets the maximum number of rounds */
	void setComplexity ( int size );
};


} // namespace

#endif