rf203_ranges.C

Go to the documentation of this file.

/// \file
/// \ingroup tutorial_roofit
/// \notebook -js
///  'ADDITION AND CONVOLUTION' RooFit tutorial macro #203
///
///  Fitting and plotting in sub ranges
///
/// \macro_image
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke 


#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooConstVar.h"
#include "RooPolynomial.h"
#include "RooAddPdf.h"
#include "RooFitResult.h"
#include "RooPlot.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TH1.h"
using namespace RooFit ;


void rf203_ranges()
{
   // S e t u p   m o d e l 
   // ---------------------

   // Construct observables x
   RooRealVar x("x","x",-10,10) ;

   // Construct gaussx(x,mx,1)
   RooRealVar mx("mx","mx",0,-10,10) ;
   RooGaussian gx("gx","gx",x,mx,RooConst(1)) ;

   // Construct px = 1 (flat in x)
   RooPolynomial px("px","px",x) ;

   // Construct model = f*gx + (1-f)px
   RooRealVar f("f","f",0.,1.) ;
   RooAddPdf model("model","model",RooArgList(gx,px),f) ;

   // Generated 10000 events in (x,y) from p.d.f. model
   RooDataSet* modelData = model.generate(x,10000) ;

   // F i t   f u l l   r a n g e 
   // ---------------------------

   // Fit p.d.f to all data
   RooFitResult* r_full = model.fitTo(*modelData,Save(kTRUE)) ;


   // F i t   p a r t i a l   r a n g e 
   // ----------------------------------

   // Define "signal" range in x as [-3,3]
   x.setRange("signal",-3,3) ;  

   // Fit p.d.f only to data in "signal" range
   RooFitResult* r_sig = model.fitTo(*modelData,Save(kTRUE),Range("signal")) ;


   // P l o t   /   p r i n t   r e s u l t s 
   // ---------------------------------------

   // Make plot frame in x and add data and fitted model
   RooPlot* frame = x.frame(Title("Fitting a sub range")) ;
   modelData->plotOn(frame) ;
   model.plotOn(frame,Range("Full"),LineStyle(kDashed),LineColor(kRed)) ; // Add shape in full ranged dashed
   model.plotOn(frame) ; // By default only fitted range is shown

   // Print fit results 
   cout << "result of fit on all data " << endl ;
   r_full->Print() ;  
   cout << "result of fit in in signal region (note increased error on signal fraction)" << endl ;
   r_sig->Print() ;

   // Draw frame on canvas
   new TCanvas("rf203_ranges","rf203_ranges",600,600) ;
   gPad->SetLeftMargin(0.15) ; frame->GetYaxis()->SetTitleOffset(1.4) ; frame->Draw() ;

   return ;

}