source: trunk/yat/statistics/ROCscore.cc @ 779

// $Id: ROCscore.cc 779 2007-03-05 18:58:30Z peter $

/*
  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 "ROCscore.h"
#include "yat/classifier/DataLookupWeighted1D.h"
#include "yat/classifier/Target.h"
#include "yat/utility/stl_utility.h"
#include "yat/utility/vector.h"

#include <cassert>
#include <cmath>
#include <utility>
#include <map>

namespace theplu {
namespace yat {
namespace statistics {  

  ROCscore::ROCscore(bool absolute)
    : Score(absolute)
  {
  }

  double ROCscore::score(const classifier::Target& target, 
                         const utility::vector& value) const
  {
    assert(target.size()==value.size());
    // key data, pair<target, weight>
    std::multimap<double, std::pair<bool, double> > m;
    for (unsigned int i=0; i<target.size(); i++)
      m.insert(std::make_pair(value(i), 
                              std::make_pair(target.binary(i),1.0)));
        
    return score(m);
  }



  double ROCscore::score(const classifier::Target& target, 
                         const classifier::DataLookupWeighted1D& value) const
  {
    assert(target.size()==value.size());
    // key data, pair<target, weight>
    std::multimap<double, std::pair<bool, double> > m;
    for (unsigned int i=0; i<target.size(); i++)
      if (value.weight(i))
        m.insert(std::make_pair(value.data(i), 
                                std::make_pair(target.binary(i), 
                                               value.weight(i))));
        
    return score(m);
  }


  double ROCscore::score(const classifier::Target& target, 
                         const utility::vector& value, 
                         const utility::vector& weight) const
  {
    assert(target.size()==value.size());
    assert(target.size()==weight.size());
    // key data, pair<target, weight>
    std::multimap<double, std::pair<bool, double> > m;
    for (unsigned int i=0; i<target.size(); i++)
      if (weight(i))
        m.insert(std::make_pair(value(i), 
                                std::make_pair(target.binary(i), weight(i))));
        
    return score(m);
  }


  double 
  ROCscore::score(const MultiMap& m) const
  {
    double area=0;
    double cumsum_pos_w=0;
    double cumsum_neg_w=0;
    typedef MultiMap::const_iterator iter;

    for (iter i=m.begin(); i!=m.end(); ++i)
      if (i->second.first){
        area += i->second.second * cumsum_neg_w;
        cumsum_pos_w += i->second.second;
      }
      else
        cumsum_neg_w += i->second.second;

    // max area is cumsum_neg_w * cumsum_pos_w
    area/=(cumsum_neg_w*cumsum_pos_w);
    
    if (area<0.5 && absolute_)
      return 1.0-area;
    return area;
}

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