estarlight/utils/AnalyzeTree.cxx

0001 // This macro reads the starlight.root file produced by convertStarlightAsciiToTree.C,
0002 // which contains TLorentzVectors for the parents and a TClonesArray of TLorentzVectors
0003 // for the daughters.
0004 //
0005 // It creates histograms of the p_T and rapidity of the daughters, as well as the p_T,
0006 // rapidity and mass of the parent.  While the parents may have been created as the
0007 // vector sum of any number of daughter particles, this macro currently produces
0008 // histograms for only the first two daughter particles.  The daughter histograms are
0009 // called D1Pt, D2Pt, D1Rapidity, and D1Rapidity.  Parent histograms are
0010 // named ParentPt, ParentRapidity, and ParentMass.  The histograms are stored in
0011 // starlight_histos.root.
0012 //
0013 // To use this macro, you must first run convertStarlightAsciiToTree.C to produce the
0014 // starlight.root file.  If needed, modify the file AnalyzeTree.h to call your input file
0015 // (as downloaded, it calls starlight.root).  Then open root and type .x anaTree.C .
0016
0017 #define AnalyzeTree_cxx
0018 #include "AnalyzeTree.h"
0019 #include <TH2.h>
0020 #include <TStyle.h>
0021 #include <TCanvas.h>
0022 #include <TLorentzVector.h>
0023 #include <iostream>
0024
0025 void AnalyzeTree::Loop()
0026 {
0027 //   In a ROOT session, you can do:
0028 //      Root > .L MyClass.C
0029 //      Root > MyClass t
0030 //      Root > t.GetEntry(12); // Fill t data members with entry number 12
0031 //      Root > t.Show();       // Show values of entry 12
0032 //      Root > t.Show(16);     // Read and show values of entry 16
0033 //      Root > t.Loop();       // Loop on all entries
0034 //
0035
0036 //     This is the loop skeleton where:
0037 //    jentry is the global entry number in the chain
0038 //    ientry is the entry number in the current Tree
0039 //  Note that the argument to GetEntry must be:
0040 //    jentry for TChain::GetEntry
0041 //    ientry for TTree::GetEntry and TBranch::GetEntry
0042 //
0043 //       To read only selected branches, Insert statements like:
0044 // METHOD1:
0045 //    fChain->SetBranchStatus("*",0);  // disable all branches
0046 //    fChain->SetBranchStatus("branchname",1);  // activate branchname
0047 // METHOD2: replace line
0048 //    fChain->GetEntry(jentry);       //read all branches
0049 //by  b_branchname->GetEntry(ientry); //read only this branch
0050    if (fChain == 0) return;
0051
0052 //  define histos
0053     TH1D* D1Prapidity     = new TH1D("D1Prapidity","Prapidity of Daughter 1",200, -10, 10);
0054     TH1D* D1Pt     = new TH1D("D1Pt","Transverse Momentum of Daughter 1",100, 0, 2.);
0055     TH1D* D2Prapidity     = new TH1D("D2Prapidity","Prapidity of Daughter 2",200, -10, 10);
0056     TH1D* D2Pt     = new TH1D("D2Pt","Transverse Momentum of Daughter 2",100, 0, 2.);
0057     TH1D* ParentRapidity     = new TH1D("ParentRapidity","Rapidity of Parent",200, -10, 10);
0058     TH1D* ParentPt     = new TH1D("ParentPt","Transverse Momentum of Parent",100, 0, 2.);
0059     TH1D* ParentMass     = new TH1D("ParentMass","Invariant Mass of Parent",100, 0, 5.);
0060
0061 // Fill histograms
0062    Long64_t nentries = fChain->GetEntriesFast();
0063
0064    Long64_t nbytes = 0, nb = 0;
0065    for (Long64_t jentry=0; jentry<nentries;jentry++) {
0066       Long64_t ientry = LoadTree(jentry);
0067       if (ientry < 0) break;
0068       nb = fChain->GetEntry(jentry);   nbytes += nb;
0069     // if desired, acceptance or analysis cuts can be applied here, before filling histograms
0070       // if (Cut(ientry) < 0) continue;
0071     D1Prapidity->Fill( p1prap_ );
0072     D2Prapidity->Fill( p2prap_ );
0073     D1Pt->Fill( p1pt_ );
0074     D2Pt->Fill( p2pt_ );
0075     ParentRapidity->Fill( fsrap_ );
0076     ParentPt->Fill( fspt_ );
0077     ParentMass->Fill( fsmass_ );
0078    }// jentry
0079
0080
0081 // write out the histos
0082      TFile *histofile = new TFile("starlight_histos.root","recreate");
0083 //     f->cd;
0084
0085     D1Prapidity->Write();
0086     D2Prapidity->Write();
0087     D1Pt->Write();
0088     D2Pt->Write();
0089     ParentRapidity->Write();
0090     ParentPt->Write();
0091     ParentMass->Write();
0092
0093      histofile->Save();
0094      histofile->Close();
0095
0096 }