STK_PoissonBase.h

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/*--------------------------------------------------------------------*/
/*     Copyright (C) 2004-2016 Serge Iovleff
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as
    published by the Free Software Foundation; either version 2 of the
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    This program 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 Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with this program; if not, write to the
    Free Software Foundation, Inc.,
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    Contact : S..._DOT_I..._AT_stkpp.org (see copyright for ...)
*/
 
/* Project:  stkpp::Clustering
 * created on: Dec 9, 2014
 * Authors: Serge Iovleff
 **/
 
#ifndef STK_POISSONBASE_H
#define STK_POISSONBASE_H
 
#include "../STK_IMixtureDensity.h"
 
#include <STatistiK/include/STK_Law_Poisson.h>
#include "../PoissonModels/STK_PoissonParameters.h"
 
namespace STK
{
template<class Derived>
class PoissonBase: public IMixtureDensity<Derived >
{
  public:
    typedef IMixtureDensity<Derived > Base;
    using Base::param_;
    using Base::p_data;
    using Base::nbCluster;
 
  protected:
    PoissonBase( int nbCluster): Base(nbCluster) {}
    PoissonBase( PoissonBase const& model): Base(model) {}
    ~PoissonBase() {}
 
  public:
    inline Real lambda(int k, int j) const { return param_.lambda(k,j);}
    void initializeModelImpl() { param_.resize(p_data()->cols());}
    Real lnComponentProbability(int i, int k) const;
    template<class Weights>
    int impute(int i, int j, Weights const& pk) const;
    Real impute(int i, int j, CArrayXX const*  p_tik) const;
    inline int rand(int i, int j, int k) const
    { return Law::Poisson::rand(lambda(k,j));}
    template<class Array>
    void getParameters(Array& params) const;
    void writeParameters(CArrayXX const* p_tik, ostream& os) const;
};
 
/* @return the value of the probability of the i-th sample in the k-th component.
 *  @param i,k indexes of the sample and of the component
 **/
template<class Derived>
Real PoissonBase<Derived>::lnComponentProbability(int i, int k) const
{
  Real sum =0.;
  for (int j=p_data()->beginCols(); j<p_data()->endCols(); ++j)
  {
    Real value = lambda(k,j);
    if (value)
    { sum += Law::Poisson::lpdf(p_data()->elt(i,j), value);}
  }
  return sum;
}
/* Implementation  */
template<class Derived>
template<class Weights>
int PoissonBase<Derived>::impute(int i, int j, Weights const& pk) const
{
  Real sum = 0.;
  for (int k= pk.begin(); k < pk.end(); ++k)
  { sum += pk[k] * lambda(k,j);}
  return std::floor(sum+0.5);
}
 
/* @return a value to impute for the jth variable of the ith sample*/
template<class Derived>
Real PoissonBase<Derived>::impute(int i, int j, CArrayXX const*  p_tik) const
{
  Real sum = 0.;
  for (int k= p_tik->beginCols(); k < p_tik->endCols(); ++k)
  { sum += p_tik->elt(i,k) * lambda(k,j);}
  return sum;
}
 
/* This function is used in order to get the current values of the lambdas.
 *  @param[out] params the array with the parameters of the mixture.
 */
template<class Derived>
template<class Array>
void PoissonBase<Derived>::getParameters(Array& params) const
{
  params.resize(nbCluster(), p_data()->cols());
  for (int k= params.beginRows(); k < params.endRows(); ++k)
  {
    for (int j= p_data()->beginCols();  j < p_data()->endCols(); ++j)
    { params(k, j) = lambda(k,j);}
  }
}
 
 
/* This function can be used to write summary of parameters to the output stream.
 *  @param p_tik a constant pointer on the posterior probabilities
 *  @param os Stream where you want to write the summary of parameters.
 */
template<class Derived>
void PoissonBase<Derived>::writeParameters(CArrayXX const* p_tik, ostream& os) const
{
  CPointX params(p_data()->cols());
  for (int k= p_tik->beginCols(); k < p_tik->endCols(); ++k)
  {
    for (int j= p_data()->beginCols();  j < p_data()->endCols(); ++j)
    { params[j] = lambda(k,j);}
    os << _T("---> Component ") << k << _T("\n");
    os << _T("lambda = ") << params;
  }
}
 
 
} // namespace STK
 
#endif /* STK_PoissonBASE_H */