RooEffGenContext.cxx

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/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitCore                                                       *
 * @(#)root/roofitcore:$Id$
 * Authors:                                                                  *
 *   GR, Gerhard Raven, NIKHEF/VU, Gerhard.Raven@nikhf.nl                    *
 *                                                                           *
 * Copyright (c) 2005, NIKHEF.  All rights reserved.                         *
 *                                                                           *
 * Redistribution and use in source and binary forms,                        *
 * with or without modification, are permitted according to the terms        *
 * listed in LICENSE (http://roofit.sourceforge.net/license.txt)             *
 *****************************************************************************/
 
/**
\file RooEffGenContext.cxx
\class RooEffGenContext
\ingroup Roofitcore
 
Specialized generator context for p.d.fs represented
by class RooEffProd, which are p.d.fs multiplied with an efficiency function.
This generator context generates events from such products by first
generating events from a dedicated generator context of the input p.d.f.
and applying an extra rejection step based on the efficiency function.
**/
 
#include <memory>
 
#include "RooEffGenContext.h"
#include "RooAbsPdf.h"
#include "RooRandom.h"
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor of generator context for RooEffProd products
 
RooEffGenContext::RooEffGenContext(const RooAbsPdf &model, const RooAbsPdf &pdf, const RooAbsReal &eff,
                                   const RooArgSet &vars, const RooDataSet *prototype, const RooArgSet *auxProto,
                                   bool verbose, const RooArgSet * /*forceDirect*/)
   : RooAbsGenContext(model, vars, prototype, auxProto, verbose), _maxEff(0.)
{
   RooArgSet x(eff, eff.GetName());
   x.snapshot(_cloneSet, true);
   initializeEff(eff);
   _generator = std::unique_ptr<RooAbsGenContext>{pdf.genContext(vars, prototype, auxProto, verbose)};
   vars.snapshot(_vars, true);
}
 
////////////////////////////////////////////////////////////////////////////////
/// One-time initialization of generator.
 
void RooEffGenContext::initGenerator(const RooArgSet &theEvent)
{
   _eff->recursiveRedirectServers(theEvent);
   _generator->initGenerator(theEvent);
 
   // Check if PDF supports maximum finding
   Int_t code = _eff->getMaxVal(_vars);
   if (!code) {
      _maxEff = 1.;
   } else {
      _maxEff = _eff->maxVal(code);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Generate one event. Generate an event from the p.d.f and
/// then perform an accept/reject sampling based on the efficiency
/// function
 
void RooEffGenContext::generateEvent(RooArgSet &theEvent, Int_t remaining)
{
   while (true) {
      _generator->generateEvent(theEvent, remaining);
      double val = _eff->getVal();
      if (val > _maxEff && !_eff->getMaxVal(_vars)) {
         coutE(Generation) << ClassName() << "::" << GetName()
                           << ":generateEvent: value of efficiency is larger than assumed maximum of 1." << std::endl;
         continue;
      }
      if (val > RooRandom::uniform() * _maxEff) {
         break;
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Detailed printing interface
 
void RooEffGenContext::printMultiline(std::ostream &os, Int_t content, bool verbose, TString indent) const
{
   RooAbsGenContext::printMultiline(os, content, verbose, indent);
   os << indent << "--- RooEffGenContext ---" << std::endl;
   os << indent << "Using EFF ";
   _eff->printStream(os, kName | kArgs | kClassName, kSingleLine, indent);
   os << indent << "PDF generator" << std::endl;
 
   TString indent2(indent);
   indent2.Append("    ");
 
   _generator->printMultiline(os, content, verbose, indent2);
}