Hi,
I’ve created a tree with splitlevel=99, and have added (two) branches of TVector3. I would like to be able to access the coordinates inside the TVector3 directly rather than loading the TVector3 and reading the member variable. The reason for this is that I’m writing a user level function so that the use can pass the variable on the command line without there being a lot of if checks inside.
Example of what I want
making the tree
//initialise atom
Double_t y[6];
y[0] = 0.0;
y[1] = 100e-6;
y[2] = 100e-6;
y[3] = 1e-4;
y[4] = 0.;
y[5] = 0.;
Double_t energy(0.);
Double_t t(0.);
//Setup for output
TFile* fid = new TFile("data/output2.root", "RECREATE");
TTree *tree = new TTree();
TVector3 *pos = new TVector3();
TVector3 *vel = new TVector3();
tree->Branch("r.", "TVector3", &pos);
tree->Branch("v.", "TVector3", &vel);
tree->Branch("t", &t, "T/D");
tree->Branch("energy", &energy, "E/D");
//runge-kutta loop
Int_t counter(0);
while(t<1e-2)
{
RK4Step(y, t, p->Dt(), p);
// things happen here....
energy = Energy(y, t, p);
pos->SetXYZ(y[0], y[1], y[2]);
vel->SetXYZ(y[3], y[4], y[5]);
tree->Fill();
t+=p->Dt();
counter++;
}
fid->WriteObject(tree, "tree");
fid->Close();
}reading the tree
DrawVsT(TString filename, Option_t* varname)
{
TFile* fid = new TFile(filename);
TTree* tree = (TTree*) fid->Get("tree");
Double_t t;
Double_t var;
tree->SetBranchAddress("t", &t);
tree->SetBranchAddress(varname, &var);
TGraph* g = new TGraph(tree->GetEntries());
for(Int_t i=0; i<tree->GetEntries(); i++)
{
tree->GetEntry(i);
printf("%f\t %f\n", t, var);
g->SetPoint(i,t,var);
}
g->Draw("ALP");
}In the root file, I can see that the TVectors have been filled. However trying to access them with varname = “r.fX” just gets me zeros. Can I make this work?