testUnfold4.C File Reference

Detailed Description

Test program for the class TUnfoldSys.

Simple toy tests of the TUnfold package

Pseudo data (5000 events) are unfolded into three components The unfolding is performed once without and once with area constraint

Ideally, the pulls may show that the result is biased if no constraint is applied. This is expected because the true data errors are not known, and instead the sqrt(data) errors are used.

 
#include <TMath.h>
#include <TCanvas.h>
#include <TRandom3.h>
#include <TF1.h>
#include <TStyle.h>
#include <TVector.h>
#include <TGraph.h>
#include <TError.h>
 
#include "TUnfoldDensity.h"
 
using std::cout;
 
TRandom *rnd=nullptr;
 
Int_t GenerateGenEvent(Int_t nmax,const Double_t *probability) {
   // choose an integer random number in the range [0,nmax]
   //    (the generator level bin)
   // depending on the probabilities
   //   probability[0],probability[1],...probability[nmax-1]
   Double_t f=rnd->Rndm();
   Int_t r=0;
   while((r<nmax)&&(f>=probability[r])) {
      f -= probability[r];
      r++;
   }
   return r;
}
 
Double_t GenerateRecEvent(const Double_t *shapeParm) {
   // return a coordinate (the reconstructed variable)
   // depending on shapeParm[]
   //  shapeParm[0]: fraction of events with Gaussian distribution
   //  shapeParm[1]: mean of Gaussian
   //  shapeParm[2]: width of Gaussian
   //  (1-shapeParm[0]): fraction of events with flat distribution
   //  shapeParm[3]: minimum of flat component
   //  shapeParm[4]: maximum of flat component
   Double_t f=rnd->Rndm();
   Double_t r;
   if(f<shapeParm[0]) {
      r=rnd->Gaus(shapeParm[1],shapeParm[2]);
   } else {
      r=rnd->Rndm()*(shapeParm[4]-shapeParm[3])+shapeParm[3];
   }
   return r;
}
 
void testUnfold4(bool printInfo = false)
{
 
   // switch off printing Info messages
   if (!printInfo) gErrorIgnoreLevel = kWarning;
 
  // switch on histogram errors
  TH1::SetDefaultSumw2();
 
  // random generator
  rnd=new TRandom3();
 
  // data and MC number of events
  Double_t const nData0=    500.0;
  Double_t const nMC0  =  50000.0;
 
  // Binning
  // reconstructed variable (0-10)
  Int_t const nDet=15;
  Double_t const xminDet=0.0;
  Double_t const xmaxDet=15.0;
 
  // signal binning (three shapes: 0,1,2)
  Int_t const nGen=3;
  Double_t const xminGen=-0.5;
  Double_t const xmaxGen= 2.5;
 
  // parameters
  // fraction of events per signal shape
  static const Double_t genFrac[]={0.3,0.6,0.1};
 
  // signal shapes
  static const Double_t genShape[][5]=
     {{1.0,2.0,1.5,0.,15.},
      {1.0,7.0,2.5,0.,15.},
      {0.0,0.0,0.0,0.,15.}};
 
  // define DATA histograms
  // observed data distribution
  TH1D *histDetDATA=new TH1D("Yrec",";DATA(Yrec)",nDet,xminDet,xmaxDet);
 
  // define MC histograms
  // matrix of migrations
  TH2D *histGenDetMC=new TH2D("Yrec%Xgen","MC(Xgen,Yrec)",
                              nGen,xminGen,xmaxGen,nDet,xminDet,xmaxDet);
 
  TH1D *histUnfold=new TH1D("Xgen",";DATA(Xgen)",nGen,xminGen,xmaxGen);
 
  TH1D **histPullNC=new TH1D* [nGen];
  TH1D **histPullArea=new TH1D* [nGen];
  for(int i=0;i<nGen;i++) {
     histPullNC[i]=new TH1D(TString::Format("PullNC%d",i),"pull",15,-3.,3.);
     histPullArea[i]=new TH1D(TString::Format("PullArea%d",i),"pull",15,-3.,3.);
  }
 
  // this method is new in version 16 of TUnfold
  cout<<"TUnfold version is "<<TUnfold::GetTUnfoldVersion()<<"\n";
 
  for(int itoy=0;itoy<1000;itoy++) {
     if(!(itoy %10)) cout<<"toy iteration: "<<itoy<<"\n";
     histDetDATA->Reset();
     histGenDetMC->Reset();
 
     Int_t nData=rnd->Poisson(nData0);
     for(Int_t i=0;i<nData;i++) {
        Int_t iGen=GenerateGenEvent(nGen,genFrac);
        Double_t yObs=GenerateRecEvent(genShape[iGen]);
        histDetDATA->Fill(yObs);
     }
 
     Int_t nMC=rnd->Poisson(nMC0);
     for(Int_t i=0;i<nMC;i++) {
        Int_t iGen=GenerateGenEvent(nGen,genFrac);
        Double_t yObs=GenerateRecEvent(genShape[iGen]);
        histGenDetMC->Fill(iGen,yObs);
     }
     /* for(Int_t ix=0;ix<=histGenDetMC->GetNbinsX()+1;ix++) {
        for(Int_t iy=0;iy<=histGenDetMC->GetNbinsY()+1;iy++) {
           cout<<ix<<iy<<" : "<<histGenDetMC->GetBinContent(ix,iy)<<"\n";
        }
        } */
     //========================
     // unfolding
 
     TUnfoldSys unfold(histGenDetMC,TUnfold::kHistMapOutputHoriz,
                       TUnfold::kRegModeSize,TUnfold::kEConstraintNone);
     // define the input vector (the measured data distribution)
     unfold.SetInput(histDetDATA,0.0,1.0);
 
     // run the unfolding
     unfold.ScanLcurve(50,0.,0.,nullptr,nullptr,nullptr);
 
     // fill pull distributions without constraint
     unfold.GetOutput(histUnfold);
 
     for(int i=0;i<nGen;i++) {
        histPullNC[i]->Fill((histUnfold->GetBinContent(i+1)-genFrac[i]*nData0)/
                            histUnfold->GetBinError(i+1));
     }
 
     // repeat unfolding on the same data, now with Area constraint
     unfold.SetConstraint(TUnfold::kEConstraintArea);
 
     // run the unfolding
     unfold.ScanLcurve(50,0.,0.,nullptr,nullptr,nullptr);
 
     // fill pull distributions with constraint
     unfold.GetOutput(histUnfold);
 
     for(int i=0;i<nGen;i++) {
        histPullArea[i]->Fill((histUnfold->GetBinContent(i+1)-genFrac[i]*nData0)/
                            histUnfold->GetBinError(i+1));
     }
 
  }
  TCanvas output;
  output.Divide(3,2);
 
  gStyle->SetOptFit(1111);
 
  for(int i=0;i<nGen;i++) {
     output.cd(i+1);
     histPullNC[i]->Fit("gaus");
     histPullNC[i]->Draw();
  }
  for(int i=0;i<nGen;i++) {
     output.cd(i+4);
     histPullArea[i]->Fit("gaus");
     histPullArea[i]->Draw();
  }
  output.SaveAs("testUnfold4.ps");
}

Version 17.6, in parallel to changes in TUnfold

History:

• Version 17.5, in parallel to changes in TUnfold
• Version 17.4, in parallel to changes in TUnfold
• Version 17.3, in parallel to changes in TUnfold
• Version 17.2, in parallel to changes in TUnfold
• Version 17.1, in parallel to changes in TUnfold
• Version 16.1, parallel to changes in TUnfold
• Version 16.0, parallel to changes in TUnfold
• Version 15, use L-curve scan to scan the average correlation

This file is part of TUnfold.

TUnfold is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

TUnfold is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with TUnfold. If not, see http://www.gnu.org/licenses/.

Author

Stefan Schmitt DESY, 14.10.2008

Definition in file testUnfold4.C.