Creating an array of the names of the histograms of a ROOT file

ROOT
1

Hello,

Is there any way to create an array of the names of the histograms of a root file from inputting the root file? I saw that there is a way to create it using TList, however, I already ran the code which took 3 days, and I do not want to rerun it again by revising the code with TList.

I am trying to create a way to save all graphs as PNG files by inputting a root file. My root file has around 100 histograms. I created a function to convert the histogram to a PNG file, however, I need to input the names of the histograms. Also, I have an older version of ROOT (5.34/10) so the rootprint command does not work for me.

Thank you very much and I really appreciate any help,
ppajarillo

ROOT Version: 5.34/10
Platform: Ubuntu 18.04 LTS
Compiler: Not Provided

2

Hello,

You can use TList::FindObject,

//TList * myHistoList = new TList();
// myHistoList->Add( ... )
TH1 * temp_h = (TH1*)myHistoList->FindObject( "myFancyHistogram" );
temp_h -> Draw();

you can store the name of the histogram (as the key) & pointer in a map,

std::map<std::string, TH1 * > myHisto_m;

//TList * myHistoList = new TList();
// myHistoList->Add( ... )
for( auto it = myHistoList->begin(); it != myHistoList->end(); ++it) 
{ 
  TH1* currentHisto = (TH1*)(*it); 
  myHisto_m.emplace( currentHisto->GetName() , currentHisto );
}
myHisto_m[ "myFancyHistogram" ]->Draw();

I don’t know if this can help.

Best regards,
atd

3

What is the obstacle which prevents you to use ROOT6 and therefore rootprint?