TTreeReader vs RDataFrame vs branches to read TTree

ROOT
,
6

It seems I can’t use TTreeReader from Python, because I can’t get the value of a TTreeReaderValue (it uses the operator ‘*’ in C++, and I don’t know how translate that to Python; I couldn’t find the answer).

ROOT.TTreeReaderValue['double']
age = ROOT.TTreeReaderValue('double')(reader, "Age")
staff_list = []
for entry in itertools.islice(tree, 10):
    # this adds just objects, need numbers
    staff_list.append(age)

I also found a suggestion by @etejedor in 2019:

…it also reads the whole branch. If you wanted to benefit from the optimization, you would need to do (from Python) SetBranchAddress + GetEntry. Alternatively, you could also use RDataFrame to efficiently read tree data from Python.