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mergeSelective.C File Reference

Detailed Description

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Merge only part of the content of a set of files.

This macro demonstrates how to merge only a part of the content of a set of input files, specified via the interface.

TFileMerger::AddObjectNames(const char *names)
void AddObjectNames(const char *name)

The method can be called several times to add object names, or using a single string with names separated by a blank. Directory names contained in the files to be merged are accepted.

Two modes are supported:

  1. kOnlyListed: via TFileMerger::PartialMerge(kOnlyListed) This will merge only the objects in the files having the names in the specified list. If a folder is specified, its whole content will be merged
  2. kSkipListed: via TFileMerger::PartialMerge(kSkipListed) This will skip merging of specified objects. If a folder is specified, its whole content will be skipped.

Important note: the kOnlyListed and kSkipListed flags have to be bitwise OR-ed on top of the merging defaults: kAll | kIncremental (as in the example)

The files to be merged have the following structure:

The example first merges exclusively hprof and the content of "folder", producing the file exclusive.root, then merges all content but skipping hprof and the content of "folder". The result can be inspected in the browser.

void CreateFile(const char *);
void mergeSelective(Int_t nfiles=5)
// Create the files to be merged
TStopwatch timer;
TString tutdir = gROOT->GetTutorialDir();
if (gROOT->LoadMacro(tutdir + "/hsimple.C")) return;
Int_t i;
for (i=0; i<nfiles; i++) CreateFile(Form("tomerge%03d.root",i));
// Merge only the listed objects
fm = new TFileMerger(kFALSE);
fm->AddObjectNames("hprof folder");
for (i=0; i<nfiles; i++) fm->AddFile(Form("tomerge%03d.root",i));
// Must add new merging flag on top of the default ones
// Skip merging of the listed objects
fm->AddObjectNames("hprof folder");
for (i=0; i<nfiles; i++) fm->AddFile(Form("tomerge%03d.root",i));
// Must add new merging flag on top of the default ones
mode = default_mode | TFileMerger::kSkipListed;
delete fm;
// Cleanup initial files
for (i=0; i<nfiles; i++) gSystem->Unlink(Form("tomerge%03d.root",i));
// Open files to inspect in the browser
new TBrowser();
void CreateFile(const char *fname)
TFile *example = (TFile*)gROOT->ProcessLineFast("hsimple(1)");
if (!example) return;
TH1F *hpx = (TH1F*)example->Get("hpx");
TFile::Cp(example->GetName(), fname);
TFile *file = TFile::Open(fname, "UPDATE");
TString sname(fname);
if (sname.Contains("000")) {
TFile::Cp(fname, "original.root");
int Int_t
Definition RtypesCore.h:45
constexpr Bool_t kFALSE
Definition RtypesCore.h:101
Option_t Option_t TPoint TPoint const char mode
#define gROOT
Definition TROOT.h:406
char * Form(const char *fmt,...)
Formats a string in a circular formatting buffer.
Definition TString.cxx:2489
R__EXTERN TSystem * gSystem
Definition TSystem.h:555
Using a TBrowser one can browse all ROOT objects.
Definition TBrowser.h:37
TDirectory * mkdir(const char *name, const char *title="", Bool_t returnExistingDirectory=kFALSE) override
Create a sub-directory "a" or a hierarchy of sub-directories "a/b/c/...".
virtual Bool_t cd()
Change current directory to "this" directory.
This class provides file copy and merging services.
Definition TFileMerger.h:30
virtual Bool_t OutputFile(const char *url, Bool_t force)
Open merger output file.
virtual Bool_t AddFile(TFile *source, Bool_t own, Bool_t cpProgress)
Add the TFile to this file merger and give ownership of the TFile to this object (unless kFALSE is re...
@ kAll
Merge all type of objects (default)
Definition TFileMerger.h:76
@ kIncremental
Merge the input file with the content of the output file (if already existing).
Definition TFileMerger.h:71
@ kSkipListed
Skip objects specified in fObjectNames list.
Definition TFileMerger.h:80
@ kOnlyListed
Only the objects specified in fObjectNames list.
Definition TFileMerger.h:79
virtual Bool_t PartialMerge(Int_t type=kAll|kIncremental)
Merge the files.
virtual void Reset()
Reset merger file list.
A ROOT file is an on-disk file, usually with extension .root, that stores objects in a file-system-li...
Definition TFile.h:53
virtual Bool_t Cp(const char *dst, Bool_t progressbar=kTRUE, UInt_t buffersize=1000000)
Allows to copy this file to the dst URL.
Definition TFile.cxx:4995
static TFile * Open(const char *name, Option_t *option="", const char *ftitle="", Int_t compress=ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault, Int_t netopt=0)
Create / open a file.
Definition TFile.cxx:4082
void Close(Option_t *option="") override
Close a file.
Definition TFile.cxx:943
1-D histogram with a float per channel (see TH1 documentation)
Definition TH1.h:621
void SetName(const char *name) override
Change the name of this histogram.
Definition TH1.cxx:8928
virtual Int_t Write(const char *name=nullptr, Int_t option=0, Int_t bufsize=0)
Write this object to the current directory.
Definition TObject.cxx:880
Stopwatch class.
Definition TStopwatch.h:28
void Start(Bool_t reset=kTRUE)
Start the stopwatch.
void Stop()
Stop the stopwatch.
void Print(Option_t *option="") const override
Print the real and cpu time passed between the start and stop events.
Basic string class.
Definition TString.h:139
virtual int Unlink(const char *name)
Unlink, i.e.
Definition TSystem.cxx:1381
The Root Team

Definition in file mergeSelective.C.