SubsampleVariable.h

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 1998 Pascal Vincent
// Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
// Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
// Copyright (C) 2002 Xiangdong Wang, Christian Dorion

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// 
//  1. Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
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/* *******************************************************      
   * $Id: SubsampleVariable.h,v 1.5 2004/04/27 16:03:35 morinf Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#ifndef SubsampleVariable_INC
#define SubsampleVariable_INC

#include "UnaryVariable.h"

namespace PLearn {
using namespace std;


class SubsampleVariable: public UnaryVariable
{
  typedef UnaryVariable inherited;

protected:
  int subsamplefactor;

public:
  SubsampleVariable() : subsamplefactor(1) {}
  SubsampleVariable(Variable* input,int the_subsamplefactor);

  PLEARN_DECLARE_OBJECT(SubsampleVariable);
  static void declareOptions(OptionList &ol);

  virtual void build();

  virtual void recomputeSize(int& l, int& w) const;
  virtual void fprop();
  virtual void bprop();
  virtual void symbolicBprop();

protected:
    void build_();
};

DECLARE_OBJECT_PTR(SubsampleVariable);

inline Var subsample(Var input, int subsample_factor)
{ return new SubsampleVariable(input, subsample_factor); }


} // end of namespace PLearn

#endif 

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