SmoothedProbSparseMatrix.h

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 2003 Christopher Kermorvant
//

// 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.
// 
//  2. Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
// 
//  3. The name of the authors may not be used to endorse or promote
//     products derived from this software without specific prior written
//     permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
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// 
// This file is part of the PLearn library. For more information on the PLearn
// library, go to the PLearn Web site at www.plearn.org

#ifndef SmoothedProbSparseMatrix_INC
#define SmoothedProbSparseMatrix_INC

#include <plearn/math/ProbSparseMatrix.h>
#include <plearn/math/TMat.h>
#define PROB_PREC 0.0001
namespace PLearn {
using namespace std;

class SmoothedProbSparseMatrix : public ProbSparseMatrix
{
protected:
  // Smoothing Method :
  // 0 : no smoothing!
  // 1 : laplace
  // 2 : discount - backoff
  // 3 :  discount - backoff non shadowing
  int smoothingMethod;  

  // Precomputed nomalization sum;
  Vec normalizationSum;
  // Backoff distribution
  Vec backoffDist;
  Vec backoffNormalization;
  // Store discounted mass in case of Backoff smoothing
  Vec discountedMass;
public:

  bool checkCondProbIntegrity();
  SmoothedProbSparseMatrix(int n_rows = 0, int n_cols = 0, string name = "pXY", int mode = ROW_WISE, bool double_access = false);
  void normalizeCondLaplace(ProbSparseMatrix& nXY, bool clear_nXY = false);
  void normalizeCondBackoff(ProbSparseMatrix& nXY, real disc, Vec& bDist,bool clear_nXY,bool shadow);
  string getClassName() const { return "SmoothedProbSparseMatrix"; }
  real get(int i,int j);
  void write(PStream& out) const;
  void read(PStream& in);

};

// WARNING : do not use this object, it is in developement. CK-11/2003
class ComplementedProbSparseMatrix : public ProbSparseMatrix
{
protected:

  real grandSum;
  Vec rowSum;
  Vec columnSum;

public:
  void complement(ProbSparseMatrix& nXY, bool clear_nXY = false);
  real get(int i,int j);
  bool checkCondProbIntegrity();
};



} // end of namespace PLearn

#endif

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