source: trunk/yat/classifier/SVindex.h @ 2986

#ifndef _theplu_yat_classifier_sv_index_ 
#define _theplu_yat_classifier_sv_index_ 

// $Id: SVindex.h 2986 2013-02-18 08:07:44Z peter $

/*
  Copyright (C) 2006, 2007, 2008 Jari Häkkinen, Peter Johansson
  Copyright (C) 2013 Jari Häkkinen

  This file is part of the yat library, http://dev.thep.lu.se/yat

  The yat library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 3 of the
  License, or (at your option) any later version.

  The yat library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with yat. If not, see <http://www.gnu.org/licenses/>.
*/

#include <cstddef>
#include <vector>

namespace theplu {
namespace yat {

namespace utility {
  class Vector;
}

namespace classifier {  

  ///
  /// \internal
  ///
  /// Internal Class keeping track of which samples are support vectors and
  /// not. The first nof_sv elements in the vector are indices of the
  /// support vectors
  ///
  class SVindex
  {

  public:
    ///Default Contructor
    SVindex(); 

    /// Constructor 
    SVindex(const size_t);

    /// @return index_first
    size_t index_first(void) const;

    /// @return index_second
    size_t index_second(void) const;

    /// synch the object against alpha
    void init(const utility::Vector& alpha, const double);

    /// @return nof support vectors
    size_t nof_sv(void) const;

    /// making first to an nsv. If already sv, nothing happens.
    void nsv_first(void);

    /// making second to an nsv. If already sv, nothing happens.
    void nsv_second(void);   

    /// randomizes the nsv part of vector and sets index_first to
    /// nof_sv_ (the first nsv)
    void shuffle(void);

    /// @return nof samples
    size_t size(void) const;

    /// making first to a sv. If already sv, nothing happens.
    void sv_first(void);

    /// making second to a sv. If already sv, nothing happens.
    void sv_second(void);

    /// set index_first to \a i
    void update_first(const size_t i);

    /// set index_second to \a i
    void update_second(const size_t i);

    /// @return value_first
    size_t value_first(void) const;

    /// @return value_second
    size_t value_second(void) const;

    /// \return index \a i (if i<nof_sv() index is sv)
    size_t operator()(size_t i) const;

  private:
    size_t index_first_;
    size_t index_second_;
    size_t nof_sv_;
    std::vector<size_t> vec_;
    size_t value_first_; // vec_[index_first_] exists for fast access
    size_t value_second_; // vec_[index_second_] exists for fast access
    
  };

}}} // of namespace classifier, yat, and theplu

#endif