doc/v606/rf702__efficiencyfit__2D_8C.html

#ifndef __CINT__

#include "RooGlobalFunc.h"

#endif

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooGaussian.h"

#include "RooConstVar.h"

#include "RooCategory.h"

#include "RooEfficiency.h"

#include "RooPolynomial.h"

#include "RooProdPdf.h"

#include "RooFormulaVar.h"

#include "TCanvas.h"

#include "TAxis.h"

#include "TH1.h"

#include "RooPlot.h"

using namespace RooFit ;


void rf702_efficiencyfit_2D(Bool_t flat=kFALSE)

{

  // C o n s t r u c t   e f f i c i e n c y   f u n c t i o n   e ( x , y )

  // -----------------------------------------------------------------------


  // Declare variables x,mean,sigma with associated name, title, initial value and allowed range

  RooRealVar x("x","x",-10,10) ;

  RooRealVar y("y","y",-10,10) ;


  // Efficiency function eff(x;a,b)

  RooRealVar ax("ax","ay",0.6,0,1) ;

  RooRealVar bx("bx","by",5) ;

  RooRealVar cx("cx","cy",-1,-10,10) ;


  RooRealVar ay("ay","ay",0.2,0,1) ;

  RooRealVar by("by","by",5) ;

  RooRealVar cy("cy","cy",-1,-10,10) ;


  RooFormulaVar effFunc("effFunc","((1-ax)+ax*cos((x-cx)/bx))*((1-ay)+ay*cos((y-cy)/by))",RooArgList(ax,bx,cx,x,ay,by,cy,y)) ;


  // Acceptance state cut (1 or 0)

  RooCategory cut("cut","cutr") ;

  cut.defineType("accept",1) ;

  cut.defineType("reject",0) ;


  // C o n s t r u c t   c o n d i t i o n a l    e f f i c i e n c y   p d f   E ( c u t | x , y )

  // ---------------------------------------------------------------------------------------------


  // Construct efficiency p.d.f eff(cut|x)

  RooEfficiency effPdf("effPdf","effPdf",effFunc,cut,"accept") ;


  // G e n e r a t e   d a t a   ( x , y , c u t )   f r o m   a   t o y   m o d e l

  // -------------------------------------------------------------------------------


  // Construct global shape p.d.f shape(x) and product model(x,cut) = eff(cut|x)*shape(x)

  // (These are _only_ needed to generate some toy MC here to be used later)

  RooPolynomial shapePdfX("shapePdfX","shapePdfX",x,RooConst(flat?0:-0.095)) ;

  RooPolynomial shapePdfY("shapePdfY","shapePdfY",y,RooConst(flat?0:+0.095)) ;

  RooProdPdf shapePdf("shapePdf","shapePdf",RooArgSet(shapePdfX,shapePdfY)) ;

  RooProdPdf model("model","model",shapePdf,Conditional(effPdf,cut)) ;


  // Generate some toy data from model

  RooDataSet* data = model.generate(RooArgSet(x,y,cut),10000) ;


  // F i t   c o n d i t i o n a l   e f f i c i e n c y   p d f   t o   d a t a

  // --------------------------------------------------------------------------


  // Fit conditional efficiency p.d.f to data

  effPdf.fitTo(*data,ConditionalObservables(RooArgSet(x,y))) ;


  // P l o t   f i t t e d ,   d a t a   e f f i c i e n c y

  // --------------------------------------------------------


  // Make 2D histograms of all data, selected data and efficiency function

  TH1* hh_data_all = data->createHistogram("hh_data_all",x,Binning(8),YVar(y,Binning(8))) ;

  TH1* hh_data_sel = data->createHistogram("hh_data_sel",x,Binning(8),YVar(y,Binning(8)),Cut("cut==cut::accept")) ;

  TH1* hh_eff      = effFunc.createHistogram("hh_eff",x,Binning(50),YVar(y,Binning(50))) ;


  // Some adjustsment for good visualization

  hh_data_all->SetMinimum(0) ;

  hh_data_sel->SetMinimum(0) ;

  hh_eff->SetMinimum(0) ;

  hh_eff->SetLineColor(kBlue) ;


  // Draw all frames on a canvas

  TCanvas* ca = new TCanvas("rf702_efficiency_2D","rf702_efficiency_2D",1200,400) ;

  ca->Divide(3) ;

  ca->cd(1) ; gPad->SetLeftMargin(0.15) ; hh_data_all->GetZaxis()->SetTitleOffset(1.8) ; hh_data_all->Draw("lego") ;

  ca->cd(2) ; gPad->SetLeftMargin(0.15) ; hh_data_sel->GetZaxis()->SetTitleOffset(1.8) ; hh_data_sel->Draw("lego") ;

  ca->cd(3) ; gPad->SetLeftMargin(0.15) ; hh_eff->GetZaxis()->SetTitleOffset(1.8) ; hh_eff->Draw("surf") ;


  return ;


}