doc/master/copytree_8C.html

// Load the library at macro parsing time: we need this to use its content in the code

R__LOAD_LIBRARY($ROOTSYS/test/libEvent.so)


void copytree()

{


   TString dir = "$ROOTSYS/test/Event.root";

   gSystem->ExpandPathName(dir);

   const auto filename = gSystem->AccessPathName(dir) ? "./Event.root" : "$ROOTSYS/test/Event.root";


   TFile oldfile(filename);

   TTree *oldtree;

   oldfile.GetObject("T", oldtree);


   // Deactivate all branches

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


   // Activate only four of them

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

      oldtree->SetBranchStatus(activeBranchName, 1);


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

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

   auto newtree = oldtree->CloneTree();


   newtree->Print();

   newfile.Write();

}

R__LOAD_LIBRARY
#define R__LOAD_LIBRARY(LIBRARY)
Definition Rtypes.h:491

filename
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t Float_t Float_t Int_t Int_t UInt_t UInt_t Rectangle_t Int_t Int_t Window_t TString Int_t GCValues_t GetPrimarySelectionOwner GetDisplay GetScreen GetColormap GetNativeEvent const char const char dpyName wid window const char font_name cursor keysym reg const char only_if_exist regb h Point_t winding char text const char depth char const char Int_t count const char ColorStruct_t color const char filename
Definition TGWin32VirtualXProxy.cxx:232

gSystem
R__EXTERN TSystem * gSystem
Definition TSystem.h:555

TFile
A ROOT file is an on-disk file, usually with extension .root, that stores objects in a file-system-li...
Definition TFile.h:53

TString
Basic string class.
Definition TString.h:139

TSystem::ExpandPathName
virtual Bool_t ExpandPathName(TString &path)
Expand a pathname getting rid of special shell characters like ~.
Definition TSystem.cxx:1274

TSystem::AccessPathName
virtual Bool_t AccessPathName(const char *path, EAccessMode mode=kFileExists)
Returns FALSE if one can access a file using the specified access mode.
Definition TSystem.cxx:1296

TTree
A TTree represents a columnar dataset.
Definition TTree.h:79

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:8534

TTree::Print
void Print(Option_t *option="") const override
Print a summary of the tree contents.
Definition TTree.cxx:7219

TTree::CloneTree
virtual TTree * CloneTree(Long64_t nentries=-1, Option_t *option="")
Create a clone of this tree and copy nentries.
Definition TTree.cxx:3139