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;
}
Peter Steinberg wrote:
>
> Hello -
>
> Now, I thought i knew how to make trees with variable length branches:
>
> 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");
>
> now when i Fill() this tree and save it to a file and then try and read it
> back
> and Draw() any of the variable-length fields, i get:
>
> root [0] TFile f("nEmcPhotons.root")
> root [1] nEmcPhotons->Draw("Pz")
> Warning in <MakeDefCanvas>: creating a default canvas with name c1
> Warning in <TBranch::GetBasket>: Estimated keylen too small=15697
> Fatal in <operator new>: storage exhausted
> aborting
>
> making bufsize=128000 in the Branch() calls does not help...
>
> - Peter