Adding a TBranch to a TChain

ROOT
1

Hello,

I want to add a TBranch to a TChain. I am trying to use the Branch routine that I use flawlessly on TTrees, filling the branch with Fill(). Everything seems to work, but when trying to access this branch, I get a segmentation fault.

I was not able to find such an example with a TChain. Is it possible to do it? Using which routines?

Many thanks,
Best,
Alex

2

Hi Alex,

For all intent and purposes TChain is designed for reading TTree (and what you are trying is not implemented). To add a branch, you will need to add it explicitly to each underlying TTree (which you can reached from chain->GetTree() … you can monitor the change over to a new TTree by checking the value of chain->GetTreeNumber()).

Cheers,
Philippe

3

Thanks Philippe,

I have had a try without success. I don’t understand how to change the ttree separately first, and access the new branch in the tchain afterwards. Do you have examples?

Thanks again,
Alex