Info lost after cloning

ROOT
1

Dear experts,

I am writing a vector, TVectorD(2), with some information to a ROOT file. The vector (called PScuts) does not appear as a branch (attached is the ROOT file for reference). When I clone the tree in order to turn off some branches I lose the vector and the information in it.
Is there a way to keep this vector after cloning the tree?

Thank you,
Amin
B-4p-0-1-v1510_14TEV_NoPileUp_288175522.PS.root (66.4 KB)

2

Hi again,

Any ideas on how to solve this issue?

Thanks a lot,
Amin

3

I suspect that is then a data member of an object that is not split. In order to keep it, you must keep the branch that contains the non-split object that contains this vector.

Cheers,
Philippe.

4

Hi Philippe,

I can’t quite follow what you exactly mean. It does not seem that this vector belong to a branch.
I tried treating it like one

oldtree->SetBranchStatus("PScuts*",1);

but it didn’t work.
If it helps, I wrote this vector to the tree using this script:

TVectorD *PScuts;
PScuts = new TVectorD(2);

for (Long64_t i=0; i<nentries; ++i) {
    chain.GetEntry(i);
    LHEFEvent *event = (LHEFEvent*) branchEvent->At(0);
    (*PScuts)(0) = (*PScuts)(0)+event->Weight;
    MissingET *met = (MissingET*) branchMissingET->At(0);
    if(met->MET<70) {continue;}
    (*PScuts)(1) = (*PScuts)(1)+event->Weight;
    newtree[0]->Fill(); }
newfile[0] = new TFile(outroot[0].c_str(),"recreate");
PScuts->Write("PScuts");
newtree[0]->Write();
newfile[0]->Close();

Thank you in advance,
Amin

5

Humm … How is newtree ‘created’?

PScuts->Write("PScuts");

ask for the TVectorD to be written ‘once’, ‘outside’ the TTree. This is unlikely to be what you meant. Nonetheless to retrieve it you would do:

TVectorD *PScuts = nullptr;
file->GetObject("PScuts", PScuts);

However it is more likely you meant to store it as part of the newtree.

Also

newfile[0] = new TFile(outroot[0].c_str(),"recreate");
...
newtree[0]->Write();

means that unless the ‘newtree’ was created as an in-memory TTree, the file will only contains the TTree meta-data and none of the data. [And if it was created as an in-memory, you may be more efficient, in run-time and memory usage, to attached it to the outputfile before filling it]

So you may have meant to do:

TVectorD *PScuts;
PScuts = new TVectorD(2);

newfile[0] = new TFile(outroot[0].c_str(),"recreate");

newtree[0] = ..... way you created the tree ... maybe ... oldtree->CloneTree(0);

newtree->Branch("PScuts",&PScuts);

for (Long64_t i=0; i<nentries; ++i) {
    chain.GetEntry(i);
    LHEFEvent *event = (LHEFEvent*) branchEvent->At(0);
    (*PScuts)(0) = (*PScuts)(0)+event->Weight;
    MissingET *met = (MissingET*) branchMissingET->At(0);
    if(met->MET<70) {continue;}
    (*PScuts)(1) = (*PScuts)(1)+event->Weight;
    newtree[0]->Fill(); 
}
newtree[0]->Write();
newfile[0]->Close();

Cheers,
Philippe.

6

Thank you @pcanal
I did mean to write the vector outside the tree. But now it seems to me that it has to be a branch and part of the tree to successfully clone it.
Yes, I created newtree the way you mentioned.
Thanks again for the help.

Best,
Amin

7

Sorry to open this up again. The branch PScuts has a lot of components which I am not familiar with (attached screenshot). In this case, how can one access the two entries of the vector?

Thank you,
Amin
branch

8

Try double clicking on fElements (towards the bottom of the list).

Cheers,
Philippe.

PS. Also see https://root.cern.ch/doc/master/classTVectorT.html

9

The histogram I see has values that do not make sense. I suppose I need to access fElements with the help of the link you provided. Maybe then I can make sense of the stored values.
Thank you again.

Best,
Amin

10

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