Ramin
July 21, 2022, 8:11am
1
Hi, all.
I was trying to read the data from a decay process that I ran in MadGraph. The result of that simulation in Madgraph gave me a TClonesArray with the name “LHEF” and several branches: Event, Rwgt, and Particle. Now I am interested in reading the information from the branch Particle, the leaf Particle.E to be exact. I have tried the following so far:
#include "TFile.h"
#include "TH1F.h"
#include "TTreeReader.h"
#include "TTreeReaderValue.h"
void electron_positron_gamma()
{
//Upload the file with the data
TFile *f = new TFile("unweighted_events.root");
//Upload the tree with the event data
TTree *LHEF = (TTree*)f->Get("LHEF");
//Calling the particle branch
TClonesArray *branchParticle = treeReader->UseBranch("Particle");
}
This gave me the following error:
I have also tried this:
void electron_positron_gamma()
{
//Upload the file with the data
TFile *f = new TFile("unweighted_events.root");
//Upload the tree with the event data
TTree *LHEF = (TTree*)f->Get("LHEF");
//Create a variable to store all the particle energies
TClonesArray *ParticleEnergy = new TClonesArray("ParticleEnergy");
}
In this case I get the following error:
Error in TClonesArray::SetClass : called with a null pointer
I have looked around and found similar issues (especially concerning my second error), but was unable to find a solution. Therefore any help will be kindly appreciated.
With kind regards,
_ROOT Version: 5.34/38
Hi @Ramin ,
As per the information that you attached, you are running ROOT 5.34. TTreeReader is only available as per ROOT6. ROOT 5.34 is not supported anymore, so I would strongly encourage you to upgrade to the latest release.
Other than that, after reading the post, the structure of your input file is not quite clear. Could you post either the file or the output of the following?
$ root your_input_file.root
root [] gFile->ls();
// We need the output of this
root [] TTree *LHEF = (TTree*)f->Get("LHEF");
root [] LHEF->Print();
// And of this
Cheers,
Ramin
July 21, 2022, 9:47am
3
Hi.
Thank you very much for the quick response!
I am working on the upgrade.
root [1] gFile->ls();
TFile** unweighted_events.root
TFile* unweighted_events.root
KEY: TTree LHEF;1 Analysis tree
root [2] TFile *f = new TFile("unweighted_events.root");
root [3] TTree *LHEF = (TTree*)f->Get("LHEF");
root [4] LHEF->Print();
******************************************************************************
*Tree :LHEF : Analysis tree *
*Entries : 198 : Total = 162685 bytes File Size = 55741 *
* : : Tree compression factor = 2.70 *
******************************************************************************
*Br 0 :Event : Int_t Event_ *
*Entries : 198 : Total Size= 7879 bytes File Size = 411 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 4.05 *
*............................................................................*
*Br 1 :Event.fUniqueID : UInt_t fUniqueID[Event_] *
*Entries : 198 : Total Size= 2268 bytes File Size = 419 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 4.00 *
*............................................................................*
*Br 2 :Event.fBits : UInt_t fBits[Event_] *
*Entries : 198 : Total Size= 2248 bytes File Size = 416 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 4.01 *
*............................................................................*
*Br 3 :Event.Number : Long64_t Number[Event_] *
*Entries : 198 : Total Size= 3045 bytes File Size = 807 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 3.05 *
*............................................................................*
*Br 4 :Event.Nparticles : Int_t Nparticles[Event_] *
*Entries : 198 : Total Size= 2273 bytes File Size = 423 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 3.96 *
*............................................................................*
*Br 5 :Event.ProcessID : Int_t ProcessID[Event_] *
*Entries : 198 : Total Size= 2268 bytes File Size = 420 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 3.99 *
*............................................................................*
*Br 6 :Event.Weight : Double_t Weight[Event_] *
*Entries : 198 : Total Size= 3045 bytes File Size = 400 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 6.16 *
*............................................................................*
*Br 7 :Event.ScalePDF : Double_t ScalePDF[Event_] *
*Entries : 198 : Total Size= 3055 bytes File Size = 401 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 6.15 *
*............................................................................*
*Br 8 :Event.CouplingQED : Double_t CouplingQED[Event_] *
*Entries : 198 : Total Size= 3070 bytes File Size = 406 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 6.08 *
*............................................................................*
*Br 9 :Event.CouplingQCD : Double_t CouplingQCD[Event_] *
*Entries : 198 : Total Size= 3070 bytes File Size = 406 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 6.08 *
*............................................................................*
*Br 10 :Event_size : Event_size/I *
*Entries : 198 : Total Size= 1363 bytes File Size = 108 *
*Baskets : 1 : Basket Size= 32000 bytes Compression= 8.05 *
*............................................................................*
*Br 11 :Rwgt : Int_t Rwgt_ *
*Entries : 198 : Total Size= 4313 bytes File Size = 405 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 4.11 *
*............................................................................*
*Br 12 :Rwgt.fUniqueID : UInt_t fUniqueID[Rwgt_] *
*Entries : 198 : Total Size= 1469 bytes File Size = 116 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 7.59 *
*............................................................................*
*Br 13 :Rwgt.fBits : UInt_t fBits[Rwgt_] *
*Entries : 198 : Total Size= 1449 bytes File Size = 112 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 7.83 *
*............................................................................*
*Br 14 :Rwgt.Weight : Double_t Weight[Rwgt_] *
*Entries : 198 : Total Size= 1454 bytes File Size = 113 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 7.77 *
*............................................................................*
*Br 15 :Rwgt_size : Rwgt_size/I *
*Entries : 198 : Total Size= 1358 bytes File Size = 104 *
*Baskets : 1 : Basket Size= 32000 bytes Compression= 8.35 *
*............................................................................*
*Br 16 :Particle : Int_t Particle_ *
*Entries : 198 : Total Size= 13831 bytes File Size = 415 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 4.02 *
*............................................................................*
*Br 17 :Particle.fUniqueID : UInt_t fUniqueID[Particle_] *
*Entries : 198 : Total Size= 4665 bytes File Size = 384 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 10.55 *
*............................................................................*
*Br 18 :Particle.fBits : UInt_t fBits[Particle_] *
*Entries : 198 : Total Size= 4645 bytes File Size = 384 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 10.54 *
*............................................................................*
*Br 19 :Particle.PID : Int_t PID[Particle_] *
*Entries : 198 : Total Size= 4635 bytes File Size = 403 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 10.04 *
*............................................................................*
*Br 20 :Particle.Status : Int_t Status[Particle_] *
*Entries : 198 : Total Size= 4650 bytes File Size = 409 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 9.90 *
*............................................................................*
*Br 21 :Particle.Mother1 : Int_t Mother1[Particle_] *
*Entries : 198 : Total Size= 4655 bytes File Size = 406 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 9.98 *
*............................................................................*
*Br 22 :Particle.Mother2 : Int_t Mother2[Particle_] *
*Entries : 198 : Total Size= 4655 bytes File Size = 383 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 10.58 *
*............................................................................*
*Br 23 :Particle.ColorLine1 : Int_t ColorLine1[Particle_] *
*Entries : 198 : Total Size= 4670 bytes File Size = 385 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 10.53 *
*............................................................................*
*Br 24 :Particle.ColorLine2 : Int_t ColorLine2[Particle_] *
*Entries : 198 : Total Size= 4670 bytes File Size = 385 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 10.53 *
*............................................................................*
*Br 25 :Particle.Px : Double_t Px[Particle_] *
*Entries : 198 : Total Size= 7798 bytes File Size = 5302 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.36 *
*............................................................................*
*Br 26 :Particle.Py : Double_t Py[Particle_] *
*Entries : 198 : Total Size= 7798 bytes File Size = 5315 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.36 *
*............................................................................*
*Br 27 :Particle.Pz : Double_t Pz[Particle_] *
*Entries : 198 : Total Size= 7798 bytes File Size = 5325 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.35 *
*............................................................................*
*Br 28 :Particle.E : Double_t E[Particle_] *
*Entries : 198 : Total Size= 7793 bytes File Size = 4583 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.57 *
*............................................................................*
*Br 29 :Particle.M : Double_t M[Particle_] *
*Entries : 198 : Total Size= 7793 bytes File Size = 471 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 15.31 *
*............................................................................*
*Br 30 :Particle.PT : Double_t PT[Particle_] *
*Entries : 198 : Total Size= 7798 bytes File Size = 5185 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.39 *
*............................................................................*
*Br 31 :Particle.Eta : Double_t Eta[Particle_] *
*Entries : 198 : Total Size= 7803 bytes File Size = 5237 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.38 *
*............................................................................*
*Br 32 :Particle.Phi : Double_t Phi[Particle_] *
*Entries : 198 : Total Size= 7803 bytes File Size = 5471 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.32 *
*............................................................................*
*Br 33 :Particle.Rapidity : Double_t Rapidity[Particle_] *
*Entries : 198 : Total Size= 7828 bytes File Size = 5230 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 1.38 *
*............................................................................*
*Br 34 :Particle.LifeTime : Double_t LifeTime[Particle_] *
*Entries : 198 : Total Size= 7828 bytes File Size = 393 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 18.37 *
*............................................................................*
*Br 35 :Particle.Spin : Double_t Spin[Particle_] *
*Entries : 198 : Total Size= 7808 bytes File Size = 584 *
*Baskets : 1 : Basket Size= 64000 bytes Compression= 12.36 *
*............................................................................*
*Br 36 :Particle_size : Particle_size/I *
*Entries : 198 : Total Size= 1378 bytes File Size = 111 *
*Baskets : 1 : Basket Size= 32000 bytes Compression= 7.86 *
*............................................................................*
I just managed to update my version of root. However, I now get the following error:
input_line_13:2:3: error: use of undeclared identifier 'treeReader'
(treeReader->UseBranch("Particle"))
I tried to solve this by this line of code:
TTreeReader treeReader("LHEF","unweighted_events.root");
, but this only worsened the situation.
With kind regards,
unweighted_events.root (61.2 KB)
It seems there are several classes involved (e.g., “TRootLHEFEvent”, “TRootWeight”, “TRootLHEFParticle”, “TSortableObject”). In order to use them, you need to load dictionaries for these classes (e.g., some shared library).
BTW. You need something like this :
TFile *f = TFile::Open("unweighted_events.root");
TTreeReader treeReader("LHEF", f);
Perhaps, additionally you might want to take a look at the TTree section in the manual: Trees - ROOT .
Cheers,
Ramin
July 21, 2022, 12:42pm
6
Hi, Wile_E_Coyote.
Thank you very much for your quick reply. I assumed that the warning about the libraries were okay (as mentioned Warning in <TClass::TClass> ). Do you mean that I should do gSystem->Load() in root with the library that I would like to load within brackets?
I tried this little piece of code and still get an error if I leave
TClonesArray *ParticleEnergy = new TClonesArray("ParticleEnergy");
in place. Is that my mistake then?
Ramin
July 21, 2022, 12:44pm
7
Thank you very much for your quick reply, jalopezg.
With kind regards,
Ramin
July 21, 2022, 1:03pm
8
Hi, all.
I have another question. Is the branch Particle.E an array of name E of type double?
With kind regards,
I guess you need to talk to your colleagues and / or your supervisor about how to deal with your data.
Ramin
July 21, 2022, 1:46pm
10
Hi, Wile_E_Coyote.
Thank you very much for reply. The thing is that I have created several trees and read data from them. This is however, the first time I encounter such a tree (it were usually trees containing branches of doubles, floats and integers). Hence my question.
With kind regards,
You maybe need a package called “ExRootAnalysis” (or “ExRoot”?), which possibly provides the “libExRootAnalysis.so” shared library (which you need to load) and the corresponding documentation for all classes and trees.
Ramin
July 22, 2022, 11:44am
12
Hi, Wile_E_Coyote.
Thanks for your reply. I have this package installed in MadGraph. All this does though, is simply storing all the data in a root file (which I posted here).
With kind regards,
pcanal
August 23, 2022, 8:12pm
13
Hi Ramin,
The package might/should also contains as part of the share library the (ROOT) dictionary representing the class that is helpful when reading (i.e. loading that library might solve your problem).
Cheers,
Ramin
September 6, 2022, 12:31pm
14
Hi pcanal,
I did indeed have to load the library before actually being able to read from the tree. Thanks a lot.
With kind regards,