How to read a std::vector values stored in TTree branch?

[dastudillo]

@utkarsh-2000

Does it mean its plotting all the entries in all the vectors ?

Do

root [ ] B5->GetEntries()

and if this number is lower than what you see in the plot, yes (unless all vectors have only 1 element or there are many empty vectors! but you get the idea).
To read the vectors and access each element, there are many examples searching this forum, for instance this:

Reading vectors from a tree

Please note that TTree::GetVal retrieves the results of the most recent TTree::Draw and nothing else. Something like this should work: vector<double> *Station = 0; t->SetBranchAddress("Station", &Station); Long64_t n = t->GetEntries(); for (Long64_t i = 0; i < n; i++) { t->GetEntry(i); ULong_t nsig = Station->size(); // MUST be done for every tree entry double *sig = Station->data(); // MUST be done for every tree entry for (ULong_t j = 0; j < nsig; j++) { std::cout << i << " : " <<…