Copy Files

Example of script showing how to copy all objects (including directories) from a source file. For each input file, a new directory is created in the current directory with the name of the source file. After the execution of:

root [0] .x copyFiles.C

the file result.root will contain 4 subdirectories: "tot100.root", "hsimple.root", "hs1.root","hs2.root"

Author: Rene Brun
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Thursday, June 17, 2021 at 04:23 PM.

In [1]:
%%cpp -d
#include "TROOT.h"
#include "TKey.h"
#include "TFile.h"
#include "TSystem.h"
#include "TTree.h"

A helper function is created:

In [2]:
%%cpp -d
void CopyDir(TDirectory *source) {
   //copy all objects and subdirs of directory source as a subdir of the current directory
   source->ls();
   TDirectory *savdir = gDirectory;
   TDirectory *adir = savdir->mkdir(source->GetName());
   adir->cd();
   //loop on all entries of this directory
   TKey *key;
   //Loop in reverse order to make sure that the order of cycles is
   //preserved.
   TIter nextkey(source->GetListOfKeys(),kIterBackward);
   while ((key = (TKey*)nextkey())) {
      const char *classname = key->GetClassName();
      TClass *cl = gROOT->GetClass(classname);
      if (!cl) continue;
      if (cl->InheritsFrom(TDirectory::Class())) {
         source->cd(key->GetName());
         TDirectory *subdir = gDirectory;
         adir->cd();
         CopyDir(subdir);
         adir->cd();
      } else if (cl->InheritsFrom(TTree::Class())) {
         TTree *T = (TTree*)source->Get(key->GetName());
         // Avoid writing the data of a TTree more than once.
         // Note this assume that older cycles are (as expected) older
         // snapshots of the TTree meta data.
         if (!adir->FindObject(key->GetName())) {
            adir->cd();
            TTree *newT = T->CloneTree(-1,"fast");
            newT->Write();
         }
      } else {
         source->cd();
         TObject *obj = key->ReadObj();
         adir->cd();
         obj->Write();
         delete obj;
     }
  }
  adir->SaveSelf(kTRUE);
  savdir->cd();
}

A helper function is created:

In [3]:
%%cpp -d
void CopyFile(const char *fname) {
   //Copy all objects and subdirs of file fname as a subdir of the current directory
   TDirectory *target = gDirectory;
   TFile *f = TFile::Open(fname);
   if (!f || f->IsZombie()) {
      printf("Cannot copy file: %s\n",fname);
      target->cd();
      return;
   }
   target->cd();
   CopyDir(f);
   delete f;
   target->cd();
}

Prepare files to be copied

In [4]:
if(gSystem->AccessPathName("tot100.root")) {
   gSystem->CopyFile("hsimple.root", "tot100.root");
   gSystem->CopyFile("hsimple.root", "hs1.root");
   gSystem->CopyFile("hsimple.root", "hs2.root");
}

Main function copying 4 files as subdirectories of a new file

In [5]:
TFile *f = new TFile("result.root","recreate");
CopyFile("tot100.root");
CopyFile("hsimple.root");
CopyFile("hs1.root");
CopyFile("hs2.root");
f->ls();
delete f;
TFile**		tot100.root	Demo ROOT file with histograms
 TFile*		tot100.root	Demo ROOT file with histograms
  KEY: TH1F	hpx;1	This is the px distribution
  KEY: TH2F	hpxpy;1	py vs px
  KEY: TProfile	hprof;1	Profile of pz versus px
  KEY: TNtuple	ntuple;1	Demo ntuple
TFile**		hsimple.root	Demo ROOT file with histograms
 TFile*		hsimple.root	Demo ROOT file with histograms
  KEY: TH1F	hpx;1	This is the px distribution
  KEY: TH2F	hpxpy;1	py vs px
  KEY: TProfile	hprof;1	Profile of pz versus px
  KEY: TNtuple	ntuple;1	Demo ntuple
TFile**		hs1.root	Demo ROOT file with histograms
 TFile*		hs1.root	Demo ROOT file with histograms
  KEY: TH1F	hpx;1	This is the px distribution
  KEY: TH2F	hpxpy;1	py vs px
  KEY: TProfile	hprof;1	Profile of pz versus px
  KEY: TNtuple	ntuple;1	Demo ntuple
TFile**		hs2.root	Demo ROOT file with histograms
 TFile*		hs2.root	Demo ROOT file with histograms
  KEY: TH1F	hpx;1	This is the px distribution
  KEY: TH2F	hpxpy;1	py vs px
  KEY: TProfile	hprof;1	Profile of pz versus px
  KEY: TNtuple	ntuple;1	Demo ntuple
TFile**		result.root	
 TFile*		result.root	
  TDirectoryFile*		tot100.root	tot100.root
   OBJ: TNtuple	ntuple	Demo ntuple : 0 at: 0x7f055ccab630
   KEY: TNtuple	ntuple;1	Demo ntuple
   KEY: TProfile	hprof;1	Profile of pz versus px
   KEY: TH2F	hpxpy;1	py vs px
   KEY: TH1F	hpx;1	This is the px distribution
  TDirectoryFile*		hsimple.root	hsimple.root
   OBJ: TNtuple	ntuple	Demo ntuple : 0 at: 0x7f055c798f00
   KEY: TNtuple	ntuple;1	Demo ntuple
   KEY: TProfile	hprof;1	Profile of pz versus px
   KEY: TH2F	hpxpy;1	py vs px
   KEY: TH1F	hpx;1	This is the px distribution
  TDirectoryFile*		hs1.root	hs1.root
   OBJ: TNtuple	ntuple	Demo ntuple : 0 at: 0x7f055c00b220
   KEY: TNtuple	ntuple;1	Demo ntuple
   KEY: TProfile	hprof;1	Profile of pz versus px
   KEY: TH2F	hpxpy;1	py vs px
   KEY: TH1F	hpx;1	This is the px distribution
  TDirectoryFile*		hs2.root	hs2.root
   OBJ: TNtuple	ntuple	Demo ntuple : 0 at: 0x7f055c708740
   KEY: TNtuple	ntuple;1	Demo ntuple
   KEY: TProfile	hprof;1	Profile of pz versus px
   KEY: TH2F	hpxpy;1	py vs px
   KEY: TH1F	hpx;1	This is the px distribution
  KEY: TDirectoryFile	tot100.root;1	tot100.root
  KEY: TDirectoryFile	hsimple.root;1	hsimple.root
  KEY: TDirectoryFile	hs1.root;1	hs1.root
  KEY: TDirectoryFile	hs2.root;1	hs2.root