Merge trees parallelly

ROOT
#1

I have a ROOT file containing two trees with different branches inside but same size (i.e. same number of events). Now I would like to merge these trees in such a way that I have all the branches from the former two in just one tree with the same event size as before. Everything I tried so far only resulted in the methods wanting to add up the events and giving error messages due to the mismatch of branch contents.

Thanks for helping!

#2

We do not have a parallel merge facility as you request. But it is better to use TTree::AddFriend and use your 2 Trees as if they were one single Tree.

Rene

#3

Ok thanks, but in fact I already tried this… Maybe I’m still doing something wrong: I want to use the MakeClass method to produce C++ code to loop over all events and have the variables from all branches of the two trees available. When I add one tree as a friend to the other and use MakeClass on the former one, the variables from the friend tree’s branches are still not available.

#4

Hi,

You need to create a MakeClass skeleton for the friend tree and tie it to the main tree’s MakeClass.

Cheers,
Philippe.

#5

Hi again,
sorry but I don’t exactly know what you mean with “tie it to the main tree’s MakeClass”?

Cheers,
Fabian