SimpleLikelihoodRatioTestStat.cxx

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// @(#)root/roostats:$Id$
// Author: Kyle Cranmer, Lorenzo Moneta, Gregory Schott, Wouter Verkerke
/*************************************************************************
 * Copyright (C) 1995-2008, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
/** \class RooStats::SimpleLikelihoodRatioTestStat
    \ingroup Roostats
 
TestStatistic class that returns -log(L[null] / L[alt]) where
L is the likelihood.
It is often called as the LEP Test statistic.
 
 
*/
 
#include "RooStats/SimpleLikelihoodRatioTestStat.h"
#include "RooStats/RooStatsUtils.h"
 
bool RooStats::SimpleLikelihoodRatioTestStat::fgAlwaysReuseNll = true ;
 
////////////////////////////////////////////////////////////////////////////////
 
void RooStats::SimpleLikelihoodRatioTestStat::SetAlwaysReuseNLL(bool flag) { fgAlwaysReuseNll = flag ; }
 
double RooStats::SimpleLikelihoodRatioTestStat::Evaluate(RooAbsData& data, RooArgSet& nullPOI) {
 
   if (fFirstEval && ParamsAreEqual()) {
      oocoutW(fNullParameters,InputArguments)
         << "Same RooArgSet used for null and alternate, so you must explicitly SetNullParameters and SetAlternateParameters or the likelihood ratio will always be 1."
         << std::endl;
   }
 
   // strip pdfs of constraints (which cancel out in the ratio) to avoid unnecessary computations and computational errors
   if (fFirstEval) {
      fNullPdf = RooStats::MakeUnconstrainedPdf(*fNullPdf, *fNullPdf->getObservables(data));
      fAltPdf  = RooStats::MakeUnconstrainedPdf(*fAltPdf , *fAltPdf->getObservables(data) );
   }
 
   fFirstEval = false;
 
   RooFit::MsgLevel msglevel = RooMsgService::instance().globalKillBelow();
   RooMsgService::instance().setGlobalKillBelow(RooFit::FATAL);
 
   bool reuse = (fReuseNll || fgAlwaysReuseNll) ;
 
   bool created = false ;
   if (!fNllNull) {
      std::unique_ptr<RooArgSet> allParams{fNullPdf->getParameters(data)};
      using namespace RooFit;
      fNllNull = std::unique_ptr<RooAbsReal>{fNullPdf->createNLL(data, CloneData(false), Constrain(*allParams), GlobalObservables(fGlobalObs), ConditionalObservables(fConditionalObs))};
      created = true ;
   }
   if (reuse && !created) {
      fNllNull->setData(data, false) ;
   }
 
   // make sure we set the variables attached to this nll
   std::unique_ptr<RooArgSet> attachedSet{fNllNull->getVariables()};
   attachedSet->assign(*fNullParameters);
   attachedSet->assign(nullPOI);
   double nullNLL = fNllNull->getVal();
 
   //std::cout << std::endl << "SLRTS: null params:" << std::endl;
   //attachedSet->Print("v");
 
 
   if (!reuse) {
      fNllNull.reset();
   }
 
   created = false ;
   if (!fNllAlt) {
      std::unique_ptr<RooArgSet> allParams{fAltPdf->getParameters(data)};
      using namespace RooFit;
      fNllAlt = std::unique_ptr<RooAbsReal>{fAltPdf->createNLL(data, CloneData(false), Constrain(*allParams), GlobalObservables(fGlobalObs), ConditionalObservables(fConditionalObs))};
      created = true ;
   }
   if (reuse && !created) {
      fNllAlt->setData(data, false) ;
   }
   // make sure we set the variables attached to this nll
   attachedSet = std::unique_ptr<RooArgSet>{fNllAlt->getVariables()};
   attachedSet->assign(*fAltParameters);
   double altNLL = fNllAlt->getVal();
 
   //std::cout << std::endl << "SLRTS: alt params:" << std::endl;
   //attachedSet->Print("v");
 
 
//   std::cout << std::endl << "SLRTS null NLL: " << nullNLL << "    alt NLL: " << altNLL << std::endl << std::endl;
 
 
   if (!reuse) {
      fNllAlt.reset();
   }
 
 
 
   // save this snapshot
   if( fDetailedOutputEnabled ) {
      if( !fDetailedOutput ) {
         fDetailedOutput = new RooArgSet( *(new RooRealVar("nullNLL","null NLL",0)), "detailedOut_SLRTS" );
         fDetailedOutput->add( *(new RooRealVar("altNLL","alternate NLL",0)) );
      }
      fDetailedOutput->setRealValue( "nullNLL", nullNLL );
      fDetailedOutput->setRealValue( "altNLL", altNLL );
 
//             std::cout << std::endl << "STORING THIS AS DETAILED OUTPUT:" << std::endl;
//             fDetailedOutput->Print("v");
//             std::cout << std::endl;
   }
 
 
   RooMsgService::instance().setGlobalKillBelow(msglevel);
   return nullNLL - altNLL;
}