Merging root files (Ttree, Tchain)

ROOT
1

Hello all,

i have several root files which contain the directory structure Event0/TreeR (here is the actual data stored).
Now i want to merge them into one root file with this kind of structure:
Event0/TreeR … (first root file from the list)
Event1/TreeR … (second…)
and so on.
But until now my root file is very small, so i guess nothing is stored.

Here is my macro:

{

ifstream fin(“cosmic_recpoints_200610XX.list”);

char filename[200];
char *chainname[700];
char treename[200];
char dirname[200];

int n=0;

TFile *newfile = new TFile(“cosmic_recpoints_200610XX.root”,“RECREATE”);
TDirectory *hdir[700];
TTree *newtree[700];

TChain chain(“TreeR”);

while (fin>>filename){

    chainname[n]=filename;
    sprintf(treename,"%s/Event0/TreeR",chainname[n]);
    sprintf(dirname,"Event%d",n);
    cout <<n<<" "<<dirname<<" "<< chainname[n]<<" "<<treename<<endl;
    chain.Add(treename);


    chain.SetBranchStatus("*",1);
                                                                                                                                                         
    hdir[n] = new TDirectory(dirname,dirname);
    hdir[n]->cd();
                                                                                                                                                         
    newtree[n] = chain.CloneTree(0);
    //newtree[n]->GetBranch("TRDcluster")->SetFile("test.root");
    newtree[n]->CopyEntries(TreeR);
    newtree[n]->Print();

    chain.Reset();
    newfile->cd();
    gDirectory->pwd();

    n++;

}
newfile->Write();

}

Thanks in advance for your replies,

best regards

2

I suggest the following simplified code:

Rene

[code]{

ifstream fin(“cosmic_recpoints_200610XX.list”);

char filename[200];

int n=0;

TFile *newfile = new TFile(“cosmic_recpoints_200610XX.root”,“RECREATE”);
TTree *tree, *newtree;

while (fin>>filename){
TFile fin = TFile::Open(filename);
if (!fin) continue;
tree = (TTree)fin->Get(“Event0/TreeR”);
newfile->cd();
TDirectory *dir = newfile->mkdir(Form(“Event%d”,n));
dir->cd();

newtree = tree->CloneTree();
newtree->Write();
gDirectory->pwd();
n++;
}
newfile->Close();

}
[/code]

3

Thanks a lot for your reply, Rene. You also work for the Alice experiment?

Best regards,

Daniel

4

yes, it happens ::slight_smile:

Rene