Ticket #45: AddFriendExample.cpp

#include <iostream>
#include <utility>
#include <vector>

#include "TROOT.h"
#include "TApplication.h"

#include "TChain.h"
#include "TString.h"

#include "TClonesArray.h"

#include "ExRootAnalysis/interface/ExRootTreeReader.h"
#include "ExRootAnalysis/interface/ExRootTreeWriter.h"
#include "ExRootAnalysis/interface/ExRootTreeBranch.h"

#include "ExRootAnalysis/interface/BlockClasses.h"

using namespace std;

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

void AnalyseEvents(ExRootTreeReader *treeReader)
{
    TClonesArray *branchElectron = treeReader->UseBranch("Electron");
    TClonesArray *branchGenParticle = treeReader->UseBranch("GEN.Particle");

    TIter itGen(branchGenParticle);
    TRootC::GenParticle *gen;

    TIter itElec(branchElectron);
    TRootElectron *elec;

    // general information
    float E,Px,Py,Pz;
    float PT,Eta,Phi;

    // lepton information
    bool IsolFlag;

    // particle level information
    int PID, Status, M1,M2,D1,D2;
    float Charge, T, X, Y, Z, M;

    Long64_t allEntries = treeReader->GetEntries();

    cout << "** Chain contains " << allEntries << " events" << endl;


    // Loop over all events
    for(Long64_t entry = 0; entry < allEntries; ++entry)
    {
        // Load selected branches with data from specified event
        treeReader->ReadEntry(entry);
        cout << "** Event contains " << branchElectron->GetEntriesFast() << " electrons" << endl;

        itGen.Reset();
        while( (gen = (TRootC::GenParticle*) itGen.Next()) )
        {
            PID      = gen->PID;      // particle HEP ID number 
            Status   = gen->Status;   // particle status 
            M1       = gen->M1;       // particle 1st mother 
            M2       = gen->M2;       // particle 2nd mother 
            D1       = gen->D1;       // particle 1st daughter 
            D2       = gen->D2;       // particle 2nd daughter 
            Charge = gen->Charge;   // electrical charge

            T      = gen->T;        // particle vertex position (t component)
            X      = gen->X;        // particle vertex position (x component) 
            Y      = gen->Y;        // particle vertex position (y component) 
            Z      = gen->Z;        // particle vertex position (z component)
            M      = gen->M;        // particle mass
        }

        // access the Electron branch
        itElec.Reset();
        while( (elec = (TRootElectron*) itElec.Next()) )
        {
            E        = elec->E;        // particle energy in GeV
            Px       = elec->Px;       // particle momentum vector (x component) in GeV
            Py       = elec->Py;       // particle momentum vector (y component) in GeV
            Pz       = elec->Pz;       // particle momentum vector (z component) in GeV

            PT       = elec->PT;       // particle transverse momentum in GeV
            Eta      = elec->Eta;      // particle pseudorapidity
            Phi      = elec->Phi;      // particle azimuthal angle in rad
            IsolFlag = elec->IsolFlag;  // is the particule isolated?
        }
    }
}

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

void AddFriendExample()
{
    TChain *chain1 = new TChain("Analysis");
    TChain *chain2 = new TChain("GEN");
    chain1->Add("tt_jj_small.root");
    chain2->Add("tt_jj_small.root");
    chain1->AddFriend(chain2, "GEN");

    ExRootTreeReader *treeReader = new ExRootTreeReader(chain1);

    AnalyseEvents(treeReader);

    cout << "** Exiting..." << endl;

    delete treeReader;
    delete chain1;
    delete chain2;
}

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

int main(int argc, char *argv[])
{
  char *appName = "AddFriendExample";

  gROOT->SetBatch();

  int appargc = 1;
  char *appargv[] = {appName};
  TApplication app(appName, &appargc, appargv);

  AddFriendExample();

}