Graph from vector inside a tree

I may be repeating things said many times, but I still cannot figure out the easiest-more straightforward way to do this:

I have a root file which has a tree, which has some leaves. I want to read the data from two of these leaves (which represent experimental data) and plot them as X, Y variables in a graph. These leaves contain data in vector or vector type.

What I do is:

vector<double> *charge;

for(UInt_t i=0; i<raw_tree->charge->size(); i++) {

unsigned int charge_size = charge.size();
TVectorT<double> tv_y(charge_size);
for ( unsigned int i=0; i<charge_size; i++) {
tv_y[i] = charge[i];

/* the same code for x axis data */ 
TGraph *g1 = new TGraph(tv_x, tv_y);
TCanvas *c1 = new TCanvas("c1", "RAW file plots", 800, 800);

The output is a graph with many points and I think it just works. Is there a way to do it without creating the
vector variable??? A more straightforward-more correct way to do it?

thank you guys
:slight_smile: :slight_smile:

p.s. I searched this forum for the key ‘graph vector’ but did not get really good results. I also think that the reference guide about TGraph does not have this info…

I just found this old post in goole(good friend)

could the TTree::Draw method be the best?