doc/hackathon/tree110__copy_8C.html

#ifdef ACTUAL_RUN  // -------- Second pass: dictionary already built --------


#include "./Event.h"  // now safe to include Event, its dictionary is loaded


void run()

{

   TFile oldfile("tree108.root");

   TTree *oldtree;

   oldfile.GetObject("t4", oldtree);


   // Deactivate all branches

   oldtree->SetBranchStatus("*", 0);


   // Activate only four of them

   for (auto activeBranchName : {"event_split", "fNtrack", "fNseg", "fH"})

      oldtree->SetBranchStatus(activeBranchName, 1);


   // Create a new file + a clone of old tree in new file

   TFile newfile("tree110.root", "recreate");

   auto newtree = oldtree->CloneTree();


   newtree->Print();

   newfile.Write();

}


#else  // -------- First pass: build dictionary + rerun macro --------


void tree110_copy()

{

   TString tutdir = gROOT->GetTutorialDir();

   gROOT->ProcessLine(".L " + tutdir + "/io/tree/Event.cxx+");

   gROOT->ProcessLine("#define ACTUAL_RUN yes");

   gROOT->ProcessLine("#include \"" __FILE__ "\"");

   gROOT->ProcessLine("run()");

}


#endif

Event.h

gROOT
#define gROOT
Definition TROOT.h:417

TFile
A file, usually with extension .root, that stores data and code in the form of serialized objects in ...
Definition TFile.h:130

TString
Basic string class.
Definition TString.h:138

TTree
A TTree represents a columnar dataset.
Definition TTree.h:89

TTree::SetBranchStatus
virtual void SetBranchStatus(const char *bname, bool status=true, UInt_t *found=nullptr)
Set branch status to Process or DoNotProcess.
Definition TTree.cxx:8779

TTree::Print
void Print(Option_t *option="") const override
Print a summary of the tree contents.
Definition TTree.cxx:7414

TTree::CloneTree
virtual TTree * CloneTree(Long64_t nentries=-1, Option_t *option="")
Create a clone of this tree and copy nentries.
Definition TTree.cxx:3173