RatioBasedFamilies.cpp

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#include "RatioBasedFamilies.h"

#include "PCSIMException.h"
#include <boost/format.hpp>

UniformDistribution RatioBasedFamilies::prob_zero_one( 0, 1 );

RatioBasedFamilies::RatioBasedFamilies( vector<double> const& ratios )
{

       if( ratios.size() < 1 ) {
         throw( PCSIM::ConstructionException( "RatioBasedFamilies::RatioBasedFamilies", str( boost::format("Empty sequence of ratios not allowed") ) ) );
       }
       probabilities.resize( ratios.size() );
       cumsum.resize( ratios.size() );
       double sum = 0.0;
       size_t i;
       for( i=0; i<ratios.size(); i++ ) {
          sum += fabs( ratios[i] );
       }
       for( i=0; i<ratios.size(); i++ ) {
          probabilities[i] = fabs( ratios[i] ) / sum;
       }
       cumsum[0] = probabilities[0];
       for( i=1; i<ratios.size(); i++ ) {
          cumsum[i] = cumsum[i-1] +  probabilities[i];
       }
}

shared_ptr< vector<familyid_t> > RatioBasedFamilies::generateIDs( SimNetwork &net, vector<SimObjectFactory *> const& families, Point3DSet const& locs ) const
{
      if( cumsum.size() != families.size() ) {
           throw( PCSIM::ConstructionException( "RatioBasedFamilies::generateIDs", str( boost::format("Number of ratios and factories/families are different.") ) ) );
      }
      shared_ptr< vector<familyid_t> > fids( new vector<familyid_t>( locs.size() ) );
      double p;
      int f;
      for( size_t i=0; i<locs.size(); i++ ) {
         p = prob_zero_one.get( *net.getMainConstructRNGEngine() );
         // For large number of families a binary search might be faster here but for low numbers ...
         for( f=0; cumsum[f]<p; f++);
         (*fids)[i] = f;
      }
      return fids;
}

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