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Reference Guide
TestSPlot.C File Reference

Detailed Description

This tutorial illustrates the use of class TSPlot and of the sPlots method

It is an example of analysis of charmless B decays, performed for BABAR. One is dealing with a data sample in which two species are present: the first is termed signal and the second background. A maximum Likelihood fit is performed to obtain the two yields N1 and N2 The fit relies on two discriminating variables collectively denoted y, which are chosen within three possible variables denoted Mes, dE and F. The variable which is not incorporated in y, is used as the control variable x. The distributions of discriminating variables and more details about the method can be found in the TSPlot class description

NOTE: This script requires a data file $ROOTSYS/tutorials/splot/TestSPlot_toyMC.dat.

View in nbviewer Open in SWAN

estimated #of events in species 0 = 462.641575
estimated #of events in species 1 = 4957.409256
estimated #of events in species 0 = 490.068958
estimated #of events in species 1 = 4929.942571
estimated #of events in species 0 = 431.484129
estimated #of events in species 1 = 4988.519463
estimated #of events in species 0 = 420.453703
estimated #of events in species 1 = 4999.547303
#include "TSPlot.h"
#include "TTree.h"
#include "TH1.h"
#include "TCanvas.h"
#include "TFile.h"
#include "TPaveLabel.h"
#include "TPad.h"
#include "TPaveText.h"
#include "Riostream.h"
void TestSPlot()
{
TString dir = gSystem->UnixPathName(__FILE__);
dir.ReplaceAll("TestSPlot.C","");
dir.ReplaceAll("/./","/");
TString dataFile = Form("%sTestSPlot_toyMC.dat",dir.Data());
//Read the data and initialize a TSPlot object
TTree *datatree = new TTree("datatree", "datatree");
datatree->ReadFile(dataFile,
"Mes/D:dE/D:F/D:MesSignal/D:MesBackground/D:dESignal/D:dEBackground/D:FSignal/D:FBackground/D",' ');
TSPlot *splot = new TSPlot(0, 3, 5420, 2, datatree);
//Set the selection for data tree
//Note the order of the variables:
//first the control variables (not presented in this example),
//then the 3 discriminating variables, then their probability distribution
//functions for the first species(signal) and then their pdfs for the
//second species(background)
"Mes:dE:F:MesSignal:dESignal:FSignal:MesBackground:"
"dEBackground:FBackground");
//Set the initial estimates of the number of events in each species
//- used as initial parameter values for the Minuit likelihood fit
Int_t ne[2];
ne[0]=500; ne[1]=5000;
//Compute the weights
splot->MakeSPlot();
//Fill the sPlots
splot->FillSWeightsHists(25);
//Now let's look at the sPlots
//The first two histograms are sPlots for the Mes variable signal and
//background. dE and F were chosen as discriminating variables to determine
//N1 and N2, through a maximum Likelihood fit, and thus the sPlots for the
//control variable Mes, unknown to the fit, was constructed.
//One can see that the sPlot for signal reproduces the PDF correctly,
//even when the latter vanishes.
//
//The lower two histograms are sPlots for the F variables signal and
//background. dE and Mes were chosen as discriminating variables to
//determine N1 and N2, through a maximum Likelihood fit, and thus the
//sPlots for the control variable F, unknown to the fit, was constructed.
TCanvas *myc = new TCanvas("myc",
"sPlots of Mes and F signal and background", 800, 600);
myc->SetFillColor(40);
TPaveText *pt = new TPaveText(0.02,0.85,0.98,0.98);
pt->SetFillColor(18);
pt->SetTextFont(20);
pt->SetTextColor(4);
pt->AddText("sPlots of Mes and F signal and background,");
pt->AddText("obtained by the tutorial TestSPlot.C on BABAR MC "
"data (sPlot_toyMC.fit)");
"M. Pivk and F. R. Le Diberder, Nucl.Inst.Meth.A, physics/0402083");
t3->SetTextColor(1);
t3->SetTextFont(30);
pt->Draw();
TPad* pad1 = new TPad("pad1","Mes signal",0.02,0.43,0.48,0.83,33);
TPad* pad2 = new TPad("pad2","Mes background",0.5,0.43,0.98,0.83,33);
TPad* pad3 = new TPad("pad3", "F signal", 0.02, 0.02, 0.48, 0.41,33);
TPad* pad4 = new TPad("pad4", "F background", 0.5, 0.02, 0.98, 0.41,33);
pad1->Draw();
pad2->Draw();
pad3->Draw();
pad4->Draw();
pad1->cd();
pad1->SetGrid();
TH1D *sweight00 = splot->GetSWeightsHist(-1, 0, 0);
sweight00->SetTitle("Mes signal");
sweight00->SetStats(kFALSE);
sweight00->Draw("e");
sweight00->SetMarkerStyle(21);
sweight00->SetMarkerSize(0.7);
sweight00->SetMarkerColor(2);
sweight00->SetLineColor(2);
sweight00->GetXaxis()->SetLabelSize(0.05);
sweight00->GetYaxis()->SetLabelSize(0.06);
sweight00->GetXaxis()->SetLabelOffset(0.02);
pad2->cd();
pad2->SetGrid();
TH1D *sweight10 = splot->GetSWeightsHist(-1, 1, 0);
sweight10->SetTitle("Mes background");
sweight10->SetStats(kFALSE);
sweight10->Draw("e");
sweight10->SetMarkerStyle(21);
sweight10->SetMarkerSize(0.7);
sweight10->SetMarkerColor(2);
sweight10->SetLineColor(2);
sweight10->GetXaxis()->SetLabelSize(0.05);
sweight10->GetYaxis()->SetLabelSize(0.06);
sweight10->GetXaxis()->SetLabelOffset(0.02);
pad3->cd();
pad3->SetGrid();
TH1D *sweight02 = splot->GetSWeightsHist(-1, 0, 2);
sweight02->SetTitle("F signal");
sweight02->SetStats(kFALSE);
sweight02->Draw("e");
sweight02->SetMarkerStyle(21);
sweight02->SetMarkerSize(0.7);
sweight02->SetMarkerColor(2);
sweight02->SetLineColor(2);
sweight02->GetXaxis()->SetLabelSize(0.06);
sweight02->GetYaxis()->SetLabelSize(0.06);
sweight02->GetXaxis()->SetLabelOffset(0.01);
pad4->cd();
pad4->SetGrid();
TH1D *sweight12 = splot->GetSWeightsHist(-1, 1, 2);
sweight12->SetTitle("F background");
sweight12->SetStats(kFALSE);
sweight12->Draw("e");
sweight12->SetMarkerStyle(21);
sweight12->SetMarkerSize(0.7);
sweight12->SetMarkerColor(2);
sweight12->SetLineColor(2);
sweight12->GetXaxis()->SetLabelSize(0.06);
sweight12->GetYaxis()->SetLabelSize(0.06);
sweight02->GetXaxis()->SetLabelOffset(0.01);
myc->cd();
}
Authors
Anna Kreshuk, Muriel Pivc

Definition in file TestSPlot.C.

TSPlot::MakeSPlot
void MakeSPlot(Option_t *option="v")
Calculates the sWeights.
Definition: TSPlot.cxx:404
TPad
Definition: TPad.h:26
TSPlot::GetSWeightsHist
TH1D * GetSWeightsHist(Int_t ixvar, Int_t ispecies, Int_t iyexcl=-1)
Returns the histogram of a variable, weighted with sWeights.
Definition: TSPlot.cxx:832
TString::Data
const char * Data() const
Definition: TString.h:369
Form
char * Form(const char *fmt,...)
TAttAxis::SetLabelOffset
virtual void SetLabelOffset(Float_t offset=0.005)
Set distance between the axis and the labels.
Definition: TAttAxis.cxx:192
TTree
Definition: TTree.h:79
TH1D
1-D histogram with a double per channel (see TH1 documentation)}
Definition: TH1.h:615
TSPlot.h
Int_t
int Int_t
Definition: RtypesCore.h:45
TPad.h
TCanvas.h
TTree.h
TString
Definition: TString.h:136
TFile.h
TPaveLabel.h
TString::ReplaceAll
TString & ReplaceAll(const TString &s1, const TString &s2)
Definition: TString.h:692
TPaveText.h
TH1::SetTitle
virtual void SetTitle(const char *title)
See GetStatOverflows for more information.
Definition: TH1.cxx:6344
TPaveText::Draw
virtual void Draw(Option_t *option="")
Draw this pavetext with its current attributes.
Definition: TPaveText.cxx:234
TAttAxis::SetLabelSize
virtual void SetLabelSize(Float_t size=0.04)
Set size of axis labels.
Definition: TAttAxis.cxx:203
TH1::GetYaxis
TAxis * GetYaxis()
Definition: TH1.h:318
TCanvas::cd
TVirtualPad * cd(Int_t subpadnumber=0)
Set current canvas & pad.
Definition: TCanvas.cxx:704
TSPlot::FillSWeightsHists
void FillSWeightsHists(Int_t nbins=50)
The order of histograms in the array:
Definition: TSPlot.cxx:698
kFALSE
const Bool_t kFALSE
Definition: RtypesCore.h:92
TSPlot
Definition: TSPlot.h:21
TH1::SetStats
virtual void SetStats(Bool_t stats=kTRUE)
Set statistics option on/off.
Definition: TH1.cxx:8445
TPaveText::AddText
virtual TText * AddText(Double_t x1, Double_t y1, const char *label)
Add a new Text line to this pavetext at given coordinates.
Definition: TPaveText.cxx:183
TSPlot::SetInitialNumbersOfSpecies
void SetInitialNumbersOfSpecies(Int_t *numbers)
Set the initial number of events of each species - used as initial estimates in minuit.
Definition: TSPlot.cxx:388
TTree::ReadFile
virtual Long64_t ReadFile(const char *filename, const char *branchDescriptor="", char delimiter=' ')
Create or simply read branches from filename.
Definition: TTree.cxx:7435
gSystem
R__EXTERN TSystem * gSystem
Definition: TSystem.h:559
TText
Definition: TText.h:22
TCanvas
Definition: TCanvas.h:23
TSystem::UnixPathName
virtual const char * UnixPathName(const char *unixpathname)
Convert from a local pathname to a Unix pathname.
Definition: TSystem.cxx:1061
TPad::cd
TVirtualPad * cd(Int_t subpadnumber=0)
Set Current pad.
Definition: TPad.cxx:594
TPad::SetGrid
virtual void SetGrid(Int_t valuex=1, Int_t valuey=1)
Definition: TPad.h:327
TPaveText
Definition: TPaveText.h:21
TSPlot::SetTreeSelection
void SetTreeSelection(const char *varexp="", const char *selection="", Long64_t firstentry=0)
Specifies the variables from the tree to be used for splot.
Definition: TSPlot.cxx:868
pt
TPaveText * pt
Definition: entrylist_figure1.C:7
TH1::GetXaxis
TAxis * GetXaxis()
Get the behaviour adopted by the object about the statoverflows. See EStatOverflows for more informat...
Definition: TH1.h:317
Riostream.h
TH1.h
TH1::Draw
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition: TH1.cxx:2997
TPad::Draw
virtual void Draw(Option_t *option="")
Draw Pad in Current pad (re-parent pad if necessary).
Definition: TPad.cxx:1285