source: branches/0.4-stable/yat/classifier/FeatureSelectorRandom.cc @ 1392

// $Id: FeatureSelectorRandom.cc 1392 2008-07-28 19:35:30Z peter $

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

  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 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>
#include <cassert>

namespace theplu {
namespace yat {
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)
  {
    std::vector<size_t>* features = new std::vector<size_t>;
    features->reserve(total_N);
    for (size_t i=0; i<total_N; ++i)
      features->push_back(i);
    // Peter should use random_sample here, but not included in std
    random::random_shuffle(features->begin(), features->end());
    features->resize(N_);
    features_ = 
      utility::Index(utility::SmartPtr<const std::vector<size_t> >(features));
  }

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