Adding data generated from a macro to a ntuple

Hello all,

I created a macro ‘deltat.C’, ran it on my file ‘file.root’ with the ntuple ‘MeritTuple’. deltat.C successfully looped over my ntuple to produce the values I wanted, but I’m not entirely sure how I can save these values to the ntuple. I know that I either need to somehow save these computed values to an ntuple and friend the two tuples together or somehow modify the original tuple to add the new data. I don’t really prefer either method (but would love to know how to do both) and am unsure how to proceed in either direction.

Suggestions or ideas?



The more flexible is to create a new TTree and make it a friend of the original:TFile *file = TFile::Open("input.root",'UPDATE"); TTree *input = 0; file->GetObject("input",input); TTree *output = new TTree("input_addition","addition to the input"); output->Branch(.....); for(Long64_t entry = 0; entry < input->GetEntries(); ++entry) { input->GetEntry(entry); // This can changed as needed to only read the needed subset. .. set the new values .. output->Fill(); } input->AddFriend(output); file->Write();

Adding a new branch is not recommended as it decreases the efficiency of reading the TTree.