DataCorr.cxx

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// $Id: DataCorr.cxx,v 1.2 2007/12/14 02:40:27 rustem Exp $

// C++
#include <cmath>

// Local
#include "DataCorr.h"

//--------------------------------------------------------------------------------------------
Anp::DataCorr::DataCorr()
   :fSampleSize(0),
    fData()
{
}

//--------------------------------------------------------------------------------------------
Anp::DataCorr::~DataCorr()
{
}

//--------------------------------------------------------------------------------------------
unsigned int Anp::DataCorr::Fill(DataIter ibeg, DataIter iend)
{
   for(DataIter xit = ibeg; xit != iend; ++xit)
   {
      const short key_x  = xit -> Key();
      const float data_x = xit -> Data();
                  
      for(DataIter yit = xit + 1; yit != iend; ++yit)
      {
         if(xit == yit)
         {
            continue;
         }

         const short key_y  = yit -> Key();
         const float data_y = yit -> Data();
         
         const Corr::Key key(key_x, key_y);
         
         Corr::Data &data = fData[key];

         data.sum_x  += data_x;
         data.sum_y  += data_y;
         data.sum_xx += data_x * data_x;
         data.sum_xy += data_x * data_y;
         data.sum_yy += data_y * data_y;
      }
   }

   return ++fSampleSize;
}

//--------------------------------------------------------------------------------------------
const Anp::Corr::CorrMap Anp::DataCorr::GetCorrCoef() const
{
   Corr::CorrMap cmap;

   if(fSampleSize < 2)
   {
      std::cerr << "DataCorr::GetCorrCoef() - sample size is too small" << std::endl;
      return cmap;
   }
   
   const double inv_size = 1.0/double(fSampleSize);
   
   for(Corr::DataMap::const_iterator dit = fData.begin(); dit != fData.end(); ++dit)
   {
      const Corr::Key &key = dit -> first;
      const Corr::Data &data = dit -> second;      

      const double nom  = data.sum_xy - data.sum_x*data.sum_y * inv_size;
      const double den1 = data.sum_xx - data.sum_x*data.sum_x * inv_size;
      const double den2 = data.sum_yy - data.sum_y*data.sum_y * inv_size;

      if(!(den1 > 0.0) || !(den2 > 0.0))
      {
         continue;       
      }

      const double corr = nom/std::sqrt(den1 * den2);

      if(!cmap.insert(Corr::CorrMap::value_type(key, corr)).second)
      {
         std::cerr << "DataCorr::GetCorrCoef() - found a duplicate key" << std::endl;
      }      
   }

   return cmap;
}

//--------------------------------------------------------------------------------------------
void Anp::DataCorr::Reset()
{
   fSampleSize = 0;
   fData.clear();
}

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