Getting a vector from TTree by its branch name

ROOT
1

Hi

This is probably a stupid question but it is taking me way too long to figure out.

I wanted to access the contents of my TTree in python using the name of the branch rather than Tree.branchname.

This is because I am trying to convert all the branches into a different structure so I wanted to do
for branchname in branches:
and do slightly different things depending on the type of the branch

For floats I can do
branchDict[branchname] = Tree.GetBranch(branchname)
and then
if branchDict[branchname].GetListOfLeaves()[0].GetTypeName() == ‘Float_t’:
value = branchDict[branchname].GetListOfLeaves()[0].GetValue()

however for those branches std::vector , I need something slightly different.
branchDict[branchname].GetObject()
seems to return a pointer but then I can’t seem to get the vector contents.

I’m sure there is some easy way to do this - so apologies(!)

Thanks

Wahid

2

Hi,

you can bind the returned pointer value using ROOT.BindObject(), which takes the address and a class name that the pointer should be bound to.

However, what is wrong with getattr(Tree, branchname)? Or if the branchname is not a string variable but the name itself, Tree.branchname? Seems easier and has better support.

Cheers,
Wim

3

Ah yes, getattr is indeed perfect for that case.
And BindObject will no doubt be useful too…

Thanks !

Wahid