Example of I/O of a mathcore Lorentz Vectors in a Tree and comparison with a TLorentzVector. A ROOT tree is written and read in both using either a XYZTVector or a TLorentzVector.
To execute the macro type in:
root[0] .x mathcoreVectorIO.C
Author: Lorenzo Moneta
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, April 17, 2024 at 11:14 AM.
%%cpp -d
#include "TRandom2.h"
#include "TStopwatch.h"
#include "TSystem.h"
#include "TFile.h"
#include "TTree.h"
#include "TH1D.h"
#include "TCanvas.h"
#include <iostream>
#include "TLorentzVector.h"
#include "Math/Vector4D.h"
using namespace ROOT::Math;
Definition of a helper function:
%%cpp -d
void write(int n) {
TRandom2 R;
TStopwatch timer;
R.SetSeed(1);
timer.Start();
double s = 0;
for (int i = 0; i < n; ++i) {
s += R.Gaus(0,10);
s += R.Gaus(0,10);
s += R.Gaus(0,10);
s += R.Gaus(100,10);
}
timer.Stop();
std::cout << s/double(n) << std::endl;
std::cout << " Time for Random gen " << timer.RealTime() << " " << timer.CpuTime() << std::endl;
TFile f1("mathcoreVectorIO_1.root","RECREATE");
// create tree
TTree t1("t1","Tree with new LorentzVector");
XYZTVector *v1 = new XYZTVector();
t1.Branch("LV branch","ROOT::Math::XYZTVector",&v1);
R.SetSeed(1);
timer.Start();
for (int i = 0; i < n; ++i) {
double Px = R.Gaus(0,10);
double Py = R.Gaus(0,10);
double Pz = R.Gaus(0,10);
double E = R.Gaus(100,10);
v1->SetCoordinates(Px,Py,Pz,E);
t1.Fill();
}
f1.Write();
timer.Stop();
std::cout << " Time for new Vector " << timer.RealTime() << " " << timer.CpuTime() << std::endl;
t1.Print();
// create tree with old LV
TFile f2("mathcoreVectorIO_2.root","RECREATE");
TTree t2("t2","Tree with TLorentzVector");
TLorentzVector * v2 = new TLorentzVector();
TLorentzVector::Class()->IgnoreTObjectStreamer();
TVector3::Class()->IgnoreTObjectStreamer();
t2.Branch("TLV branch","TLorentzVector",&v2,16000,2);
R.SetSeed(1);
timer.Start();
for (int i = 0; i < n; ++i) {
double Px = R.Gaus(0,10);
double Py = R.Gaus(0,10);
double Pz = R.Gaus(0,10);
double E = R.Gaus(100,10);
v2->SetPxPyPzE(Px,Py,Pz,E);
t2.Fill();
}
f2.Write();
timer.Stop();
std::cout << " Time for old Vector " << timer.RealTime() << " " << timer.CpuTime() << endl;
t2.Print();
}
Definition of a helper function:
%%cpp -d
void read() {
TRandom R;
TStopwatch timer;
TFile f1("mathcoreVectorIO_1.root");
// create tree
TTree *t1 = (TTree*)f1.Get("t1");
XYZTVector *v1 = 0;
t1->SetBranchAddress("LV branch",&v1);
timer.Start();
int n = (int) t1->GetEntries();
std::cout << " Tree Entries " << n << std::endl;
double etot=0;
for (int i = 0; i < n; ++i) {
t1->GetEntry(i);
etot += v1->Px();
etot += v1->Py();
etot += v1->Pz();
etot += v1->E();
}
timer.Stop();
std::cout << " Time for new Vector " << timer.RealTime() << " " << timer.CpuTime() << std::endl;
std::cout << " TOT average : n = " << n << "\t " << etot/double(n) << endl;
// create tree with old LV
TFile f2("mathcoreVectorIO_2.root");
TTree *t2 = (TTree*)f2.Get("t2");
TLorentzVector * v2 = 0;
t2->SetBranchAddress("TLV branch",&v2);
timer.Start();
n = (int) t2->GetEntries();
std::cout << " Tree Entries " << n << std::endl;
etot = 0;
for (int i = 0; i < n; ++i) {
t2->GetEntry(i);
etot += v2->Px();
etot += v2->Py();
etot += v2->Pz();
etot += v2->E();
}
timer.Stop();
std::cout << " Time for old Vector " << timer.RealTime() << " " << timer.CpuTime() << endl;
std::cout << " TOT average:\t" << etot/double(n) << endl;
}
int nEvents = 100000;
write(nEvents);
read();
99.8767 Time for Random gen 0.0162458 0.01 Time for new Vector 0.285207 0.26 ****************************************************************************** *Tree :t1 : Tree with new LorentzVector * *Entries : 100000 : Total = 3214176 bytes File Size = 2910657 * * : : Tree compression factor = 1.10 * ****************************************************************************** *Branch :LV branch * *Entries : 100000 : BranchElement (see below) * *............................................................................* *Br 0 :fCoordinates : * *Entries : 100000 : Total Size= 4720 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................* *Br 1 :fCoordinates.fX : Double_t * *Entries : 100000 : Total Size= 803057 bytes File Size = 733353 * *Baskets : 26 : Basket Size= 32000 bytes Compression= 1.09 * *............................................................................* *Br 2 :fCoordinates.fY : Double_t * *Entries : 100000 : Total Size= 803057 bytes File Size = 733905 * *Baskets : 26 : Basket Size= 32000 bytes Compression= 1.09 * *............................................................................* *Br 3 :fCoordinates.fZ : Double_t * *Entries : 100000 : Total Size= 803057 bytes File Size = 733645 * *Baskets : 26 : Basket Size= 32000 bytes Compression= 1.09 * *............................................................................* *Br 4 :fCoordinates.fT : Double_t * *Entries : 100000 : Total Size= 803057 bytes File Size = 708062 * *Baskets : 26 : Basket Size= 32000 bytes Compression= 1.13 * *............................................................................* Time for old Vector 0.210975 0.2 ****************************************************************************** *Tree :t2 : Tree with TLorentzVector * *Entries : 100000 : Total = 4835755 bytes File Size = 3369956 * * : : Tree compression factor = 1.43 * ****************************************************************************** *Br 0 :TLV branch : TLorentzVector * *Entries : 100000 : Total Size= 4835322 bytes File Size = 3366724 * *Baskets : 327 : Basket Size= 16000 bytes Compression= 1.43 * *............................................................................* Tree Entries 100000 Time for new Vector 0.0503459 0.06 TOT average : n = 100000 99.8767 Tree Entries 100000 Time for old Vector 0.0550251 0.05 TOT average: 99.8767
Warning in <TTree::Bronch>: TLorentzVector cannot be split, resetting splitlevel to 0