source: trunk/c++_tools/classifier/FeatureSelectorRandom.cc @ 675

// $Id: FeatureSelectorRandom.cc 675 2006-10-10 12:08:45Z jari $

/*
  Copyright (C) The authors contributing to this file.

  This file is part of the yat library, http://lev.thep.lu.se/trac/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 2 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 this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

#include "FeatureSelectorRandom.h"
#include "MatrixLookup.h"
#include "MatrixLookupWeighted.h"
#include "Target.h"
#include "yat/random/random.h"

#include <algorithm>

namespace theplu {
namespace classifier {


  FeatureSelectorRandom::FeatureSelectorRandom(size_t N)
    : FeatureSelector(N)
  {
  }



  void FeatureSelectorRandom::update(const MatrixLookup& data, 
                                     const Target& target)
  {
    assert(data.columns()==target.size());
    update(data.rows());
  }


  void FeatureSelectorRandom::update(const MatrixLookupWeighted& data, 
                                 const Target& target)
  {
    assert(data.columns()==target.size());
    update(data.rows());
  }


  void FeatureSelectorRandom::update(size_t total_N)
  {
    features_.resize(0);
    features_.reserve(total_N);
    for (size_t i=0; i<total_N; ++i)
      features_.push_back(i);
    random::DiscreteUniform rnd;
    // Peter should use random_sample here, but not included in std
    std::random_shuffle(features_.begin(), features_.end(), rnd);
    features_.resize(N_);
  }


} // end of namespace classifier
} // end of namespace theplu