rs602_HLFactoryCombinationexample.C

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/// \file
/// \ingroup tutorial_roostats
/// \notebook
/// High Level Factory: creation of a combined model
///
/// \macro_image
/// \macro_output
/// \macro_code
///
/// \author Danilo Piparo

#include <fstream>
#include "TString.h"
#include "TROOT.h"
#include "RooGlobalFunc.h"
#include "RooWorkspace.h"
#include "RooRealVar.h"
#include "RooAbsPdf.h"
#include "RooDataSet.h"
#include "RooPlot.h"
#include "RooStats/HLFactory.h"

// use this order for safety on library loading
using namespace RooFit;
using namespace RooStats;
using namespace std;

void rs602_HLFactoryCombinationexample()
{

   using namespace RooStats;
   using namespace RooFit;

   // create a card
   TString card_name("HLFavtoryCombinationexample.rs");
   ofstream ofile(card_name);
   ofile << "// The simplest card for combination\n\n"
         << "gauss1 = Gaussian(x[0,100],mean1[50,0,100],4);\n"
         << "flat1 = Polynomial(x,0);\n"
         << "sb_model1 = SUM(nsig1[120,0,300]*gauss1 , nbkg1[100,0,1000]*flat1);\n"
         << "gauss2 = Gaussian(x,mean2[80,0,100],5);\n"
         << "flat2 = Polynomial(x,0);\n"
         << "sb_model2 = SUM(nsig2[90,0,400]*gauss2 , nbkg2[80,0,1000]*flat2);\n";

   ofile.close();

   HLFactory hlf("HLFavtoryCombinationexample", card_name, false);

   hlf.AddChannel("model1", "sb_model1", "flat1");
   hlf.AddChannel("model2", "sb_model2", "flat2");
   auto pdf = hlf.GetTotSigBkgPdf();
   auto thecat = hlf.GetTotCategory();
   auto x = static_cast<RooRealVar *>(hlf.GetWs()->arg("x"));

   auto data = pdf->generate(RooArgSet(*x, *thecat), Extended());

   // --- Perform extended ML fit of composite PDF to toy data ---
   pdf->fitTo(*data);

   // --- Plot toy data and composite PDF overlaid ---
   auto xframe = x->frame();

   data->plotOn(xframe);
   thecat->setIndex(0);
   pdf->plotOn(xframe, Slice(*thecat), ProjWData(*thecat, *data));

   thecat->setIndex(1);
   pdf->plotOn(xframe, Slice(*thecat), ProjWData(*thecat, *data));

   gROOT->SetStyle("Plain");
   xframe->Draw();
}