OneStepMarkovChain.hpp

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/*==========================================================================
 * Copyright (c) 2001 Carnegie Mellon University.  All Rights Reserved.
 *
 * Use of the Lemur Toolkit for Language Modeling and Information Retrieval
 * is subject to the terms of the software license set forth in the LICENSE
 * file included with this software, and also available at
 * http://www.lemurproject.org/license.html
 *
 *==========================================================================
 */


#ifndef _ONESTEPMARKOVCHAIN_HPP
#define _ONESTEPMARKOVCHAIN_HPP


#include "Index.hpp"
#include "WeightedIDSet.hpp"
namespace lemur 
{
  namespace langmod
  {
    

    class OneStepMarkovChain {
    public:
      OneStepMarkovChain(const lemur::utility::WeightedIDSet &docSet, const lemur::api::Index &homeIndex, double *wdNorm, double stopProbAlpha);
      ~OneStepMarkovChain();
  


      void startFromWordIteration(lemur::api::TERMID_T toWord) const;
      bool hasMoreFromWord() const { 
        while (itPos <= ind.termCountUnique() && fromWordPr[itPos]==0) 
          itPos++;
        return (itPos<= ind.termCountUnique());
      }
      void nextFromWordProb(lemur::api::TERMID_T &fromWord, double &prob) const ;

    private:
      void computeFromWordProb(lemur::api::TERMID_T toWord) const;
      const lemur::api::Index &ind;
      double alpha;
      int *dSet;
      double *norm;
      mutable double *fromWordPr;
      mutable lemur::api::TERMID_T itPos;
      mutable lemur::api::TERMID_T curToWord;
    };
  }
}


#endif /* _ONESTEPMARKOVCHAIN_HPP */

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