Hi Stephen,
You can find an example below
Rene Brun
{
TFile *f = new TFile("peter.root","recreate");
Int_t nPhot;
Float_t E[500];
Float_t Px[500];
Float_t Py[500];
Float_t Pz[500];
Float_t Arm[500];
Float_t PhotProb[500];
TTree* nEmcPhotons = new TTree("nEmcPhotons","EMC Photons");
nEmcPhotons->Branch("nPhot",&nPhot,"nPhot/I");
nEmcPhotons->Branch("E",E,"E[nPhot]/F");
nEmcPhotons->Branch("Px",Px,"Px[nPhot]/F");
nEmcPhotons->Branch("Py",Py,"Py[nPhot]/F");
nEmcPhotons->Branch("Pz",Pz,"Pz[nPhot]/F");
nEmcPhotons->Branch("Arm", Arm,"Arm[nPhot]/F");
nEmcPhotons->Branch("PhotProb", PhotProb,"PhotProb[nPhot]/F");
for (Int_t i=0;i<1000;i++) {
nPhot = 500*gRandom->Rndm();
for (Int_t j=0;j<nPhot;j++) {
E[j] = j;
Px[j] = j+1;
Py[j] = j+2;
Pz[j] = j+3;
Arm[j] = j+4;
PhotProb[j] = j+5;
}
nEmcPhotons->Fill();
}
nEmcPhotons->Print();
nEmcPhotons->Write();
f->Close();
delete f;
}
On Sun, 29 Oct 2000, Stephen Adler wrote:
> I'm trying to build a root tree with variable length arrays. In the
> old days of paw/ntuples, using column wise ntuples, one was able to
> define an array with a length as in
>
> alen[0:250],tracks[1:alen]
>
> or something like that. I can't remember the paw/ntuple columb-wise
> syntax becuase I haven't used it in years. In anycase, I want to do
> the same with a root tree. Do I define a branch inside a branch or
> something like that?
>
> Cheers. Steve.
>
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