TopNI.h

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 1998 Pascal Vincent
// Copyright (C) 1999,2000 Pascal Vincent, Yoshua Bengio and University of Montreal
//

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// modification, are permitted provided that the following conditions are met:
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//  1. Redistributions of source code must retain the above copyright
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// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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/* *******************************************************      
   * $Id: TopNI.h,v 1.3 2004/07/21 16:30:53 chrish42 Exp $
   * AUTHORS: Yoshua Bengio
   * This file is part of the PLearn library.
   ******************************************************* */


#ifndef TopNI_INC
#define TopNI_INC

#include <plearn/base/general.h>
#include "TMat.h"

namespace PLearn {
using namespace std;

  template <class T>
  class TopNI
  {
  protected:
    int N;
    TVec< pair<T,int> > topn;
    pair<T,int>* topnptr; 
    pair<T,int>* minpair;
  
  public:

    TopNI()
    {}
    
    TopNI(int the_N) { init(the_N); }

    void init(int the_N)
    {
      N = the_N;
      topn.resize(N); 
      topn.resize(0); 
      topnptr = topn.data(); 
    }

    void reset() { init(N); }

    void update(T value, int index)
    {
      int l=topn.length();
      if(l<N)
        {
          topn.append( pair<T,int>(value,index) );
          if (l==0 || value<minpair->first)
            minpair = &topnptr[l];
        }
      else if(value>minpair->first)
        {
          minpair->first = value;
          minpair->second = index;

          pair<T,int>* it = topnptr;
          int n = N;
          while(n--)
            {
              if(it->first<minpair->first)
                minpair = it;
              ++it;
            }
        }
    }

    void sort() 
    { std::sort(topnptr, topnptr+topn.length(), greater<pair <T,int> >() ); }

    const TVec< pair<T,int> >& getTopN() { return topn; }
  };

} // end of namespace PLearn

#endif

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