source: trunk/yat/normalizer/Spearman.h @ 1507

#ifndef _theplu_yat_normalizer_spearman_
#define _theplu_yat_normalizer_spearman_

/*
  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 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 "yat/utility/iterator_traits.h"
#include "yat/utility/sort_index.h"

#include <vector>

namespace theplu {
namespace yat {
namespace normalizer {

  /**
     \brief Replace elements with normalized rank

     \since New in yat 0.5
   */
  class Spearman
  {
  public:
    /**
       \brief default constructor
     */
    Spearman(void){}

    /**
       It is possible to centralize a range "in place"; it is
       permissible for the iterators \a first and \a result to be the
       same.

       \note Currently weighted version is not implemented

       \return result + (last-first)
     */
    template<typename InputIterator, typename RandomAccessIterator>
    RandomAccessIterator operator()(InputIterator first, InputIterator last,
                                    RandomAccessIterator result) const
    {
      typename utility::weighted_iterator_traits<InputIterator>::type tag;
      return normalize(first, last, result, tag);
    }


  private:
    // unweighted version
    template<typename InputIterator, typename RandomAccessIterator>
    RandomAccessIterator normalize(InputIterator first, InputIterator last,
                                   RandomAccessIterator result, 
                                   utility::unweighted_iterator_tag) const
    {
      std::vector<size_t> perm;
      utility::sort_index(first, last, perm);
      double n = perm.size();
      for ( size_t i=0; i<perm.size(); ++i)
        result[perm[i]] = static_cast<double>(i)/n;
      return result + std::distance(first, last);
    }

  };

}}} // end of namespace normalizer, yat and thep
#endif