Logo ROOT   6.12/07
Reference Guide
copytree2.C File Reference

Detailed Description

View in nbviewer Open in SWAN Copy a subset of a Tree to a new Tree, one branch in a separate file.

One branch of the new Tree is written to a separate file The input file has been generated by the program in $ROOTSYS/test/Event with the command Event 1000 1 1 1

R__LOAD_LIBRARY($ROOTSYS/test/libEvent.so)
void copytree2() {
//Get old file, old tree and set top branch address
TFile *oldfile;
TString dir = "$ROOTSYS/test/Event.root";
if (!gSystem->AccessPathName(dir))
{oldfile = new TFile("$ROOTSYS/test/Event.root");}
else {oldfile = new TFile("./Event.root");} TTree *oldtree = (TTree*)oldfile->Get("T");
Event *event = new Event();
oldtree->SetBranchAddress("event",&event);
oldtree->SetBranchStatus("*",0);
oldtree->SetBranchStatus("event",1);
oldtree->SetBranchStatus("fNtrack",1);
oldtree->SetBranchStatus("fNseg",1);
oldtree->SetBranchStatus("fH",1);
//Create a new file + a clone of old tree header. Do not copy events
TFile *newfile = new TFile("small.root","recreate");
TTree *newtree = oldtree->CloneTree(0);
//Divert branch fH to a separate file and copy all events
newtree->GetBranch("fH")->SetFile("small_fH.root");
newtree->CopyEntries(oldtree);
newtree->Print();
newfile->Write();
delete oldfile;
delete newfile;
}
Author
Rene Brun

Definition in file copytree2.C.