source: trunk/c++_tools/classifier/CrossValidationSampler.h @ 645

#ifndef _theplu_classifier_crossvalidation_sampler_ 
#define _theplu_classifier_crossvalidation_sampler_

// $Id$

/*
  Copyright (C) 2006 Peter Johansson

  This file is part of the thep c++ tools library,
                                http://lev.thep.lu.se/trac/c++_tools

  The c++ tools 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 2 of
  the License, or (at your option) any later version.

  The c++ tools 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 this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

#include <c++_tools/classifier/Sampler.h>

namespace theplu {
namespace classifier {  

  class Target;

  ///
  /// Class splitting a set into training set and validation set in a
  /// crossvalidation manner. This is done in a balanced way, meaning
  /// the proportions between the classes in the trainingset is close
  /// to the proportions in the whole dataset. In the first \a k
  /// rounds each sample is returned k-1 times, for next round the
  /// samples are shuffled and... In total there are N partitions, in
  /// other words, each sample is in validation roughly N/k
  ///   
  class CrossValidationSampler : public Sampler
  {
  
  public:
    ///
    /// @brief Constructor 
    ///  
    /// @a target targets.    
    /// @a N total number of partitions.
    /// @a k for k-fold crossvalidation.
    ///
    CrossValidationSampler(const Target& target, const size_t N,const size_t k);

    ///
    /// Destructor
    ///
    virtual ~CrossValidationSampler();

  private:
    void build(const Target& target, size_t N, size_t k); 
    const size_t k_;

  };

}} // of namespace classifier and namespace theplu

#endif