DistSampler.cxx

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// @(#)root/mathcore:$Id$
// Author: L. Moneta Fri Sep 22 15:06:47 2006

/**********************************************************************
 *                                                                    *
 * Copyright (c) 2006  LCG ROOT Math Team, CERN/PH-SFT                *
 *                                                                    *
 *                                                                    *
 **********************************************************************/

// implementation file for class DistSampler

#include "Math/DistSampler.h"
#include "Math/DistSamplerOptions.h"
#include "Math/Error.h"

#include "Math/IFunction.h"
#include "Math/IFunctionfwd.h"
#include "Fit/BinData.h"
#include "Fit/UnBinData.h"
#include "Fit/DataRange.h"


namespace ROOT {


namespace Math {

DistSampler::~DistSampler() {
   // destructor
   if (fOwnFunc && fFunc != 0) delete fFunc;
   if (fRange) delete fRange;
}

bool DistSampler::Init(const DistSamplerOptions & opt ) {
   // default initialization with algorithm name
   return Init(opt.Algorithm().c_str() );
}

void DistSampler::SetRange(double xmin, double xmax, int icoord) {
   if (!fRange) {
      MATH_ERROR_MSG("DistSampler::SetRange","Need to set function before setting the range");
      return;
   }
   fRange->SetRange(icoord,xmin,xmax);
}

void DistSampler::SetRange(const double * xmin, const double * xmax) {
   // set range specifying a vector for all coordinates
   if (!fRange) {
      MATH_ERROR_MSG("DistSampler::SetRange","Need to set function before setting the range");
      return;
   }
   for (unsigned int icoord = 0; icoord < NDim(); ++icoord)
      fRange->SetRange(icoord,xmin[icoord],xmax[icoord]);
}

void DistSampler::SetRange(const ROOT::Fit::DataRange & range) {
   // copy the given range
   *fRange = range;
}

void DistSampler::DoSetFunction(const ROOT::Math::IMultiGenFunction & func, bool copy) {
   // set the internal function
   // if a range exists and it is compatible it will be re-used
   if (fOwnFunc && fFunc != 0) delete fFunc;
   if (copy) {
      fOwnFunc = true;
      fFunc = func.Clone();
   }
   else {
      fOwnFunc = false;
      fFunc = &func;
   }
   fData = std::vector<double>(func.NDim());
   // delete a range if exists and it is not compatible
   if (fRange && fRange->NDim() != fData.size() ) {
      delete fRange;
      fRange = 0;
   }
   if (!fRange) fRange = new ROOT::Fit::DataRange(func.NDim() );
}

bool DistSampler::IsInitialized()  {
   // test if sampler is initialized
   // tryying to generate one event (for this cannot be const)
   if (NDim() == 0) return false;
   if (fFunc == 0) return false;
   if (fFunc->NDim() != NDim() ) return false;
   // test one event
   if (!Sample(&fData[0]) ) return false;
   return true;
}

bool DistSampler::Generate(unsigned int nevt, ROOT::Fit::UnBinData & data) {
   // generate a un-binned data sets (fill the given data set)
   // if dataset has already data append to it
   if (!IsInitialized()) {
         MATH_WARN_MSG("DistSampler::Generate","sampler has not been initialized correctly");
         return false;
   }

   data.Append( nevt, NDim() );
   for (unsigned int i = 0; i < nevt; ++i) {
      const double * x = Sample();
      data.Add( x );
   }
   return true;
}


   bool DistSampler::Generate(unsigned int nevt, const  int * nbins, ROOT::Fit::BinData & data, bool extend) {
   // generate a bin data set from given bin center values
   // bin center values must be present in given data set
   //if (!IsInitialized()) {
   if (NDim() == 0 || fFunc == 0 ) {
      MATH_WARN_MSG("DistSampler::Generate","sampler has not been initialized correctly");
      return false;
   }


   int ntotbins = 1;
   for (unsigned int j = 0; j < NDim(); ++j) {
      ntotbins *= nbins[j];
   }

   data.Append(ntotbins, NDim(), ROOT::Fit::BinData::kValueError);    // store always the error
   // use for the moment bin center (should use bin integral)
   std::vector<double> dx(NDim() );
   std::vector<double> x(NDim() );
   double binVolume = 1;
   for (unsigned int j = 0; j < dx.size(); ++j) {
      double x1 = 0,x2 = 0;
      if (!fRange || !fRange->Size(j)) {
         MATH_WARN_MSG("DistSampler::Generate","sampler has not a range defined for all coordinates");
         return false;
      }
      fRange->GetRange(j,x1,x2);
      dx[j] =  (x2-x1)/double(nbins[j]);
      assert(dx[j] > 0 && 1./dx[j] > 0 ); // avoid dx <= 0 and  not inf
      x[j] = x1 + dx[j]/2;  // use bin centers
      binVolume *= dx[j];
   }
   double nnorm = nevt * binVolume;

   if (extend) {

      bool ret = true;
      for (int j = NDim()-1; j >=0; --j) {
         for (int i = 0; i < nbins[j]; ++i) {
            //const double * v = Sample();
            double val = 0;
            double eval = 0;
            double yval = (ParentPdf())(&x.front());
            double nexp = yval * nnorm;
            ret &= SampleBin(nexp,val,&eval);
            data.Add(&x.front(), val, eval);
            x[j] += dx[j]; // increment x bin the bin
         }
         if (!ret) {
            MATH_WARN_MSG("DistSampler::Generate","error returned from SampleBin");
            return false;
         }
      }
   }
   else {
      MATH_WARN_MSG("DistSampler::Generate","generation with fixed events not yet impelmented");
      return false;
   }
   return true;
}

} // end namespace Math
} // end namespace ROOT