Problem with Tree and Branch

ROOT
1

Hi everyone, I’m new in this forum and I’m looking for an help to try to solve my problem with a Tree.

I want to plot a branch of my Tree (“Events”) but if I use from terminal

Events->Draw("-channels[1].regions[0].integral")

I can obtain what I want, instead if I put it in a macro I have some problems, because I don’t know how set the address of the branch with a vector (I need Br 37!)

*Br 35 :channels.npulses : Int_t npulses[channels_] * *Entries : 500000 : Total Size= 8006413 bytes File Size = 690528 * *Baskets : 53 : Basket Size= 2052096 bytes Compression= 11.59 * *............................................................................* *Br 36 :channels.pulses : vector<Pulse> pulses[channels_] * *Entries : 500000 : Total Size= 11007924 bytes File Size = 803508 * *Baskets : 67 : Basket Size= 2821120 bytes Compression= 13.70 * *............................................................................* *Br 37 :channels.regions : vector<Roi> regions[channels_] * *Entries : 500000 : Total Size= 539262020 bytes File Size = 132591572 * *Baskets : 2572 : Basket Size= 28608512 bytes Compression= 4.07 * *............................................................................* *Br 38 :channels.single_pe : vector<Spe> single_pe[channels_] * *Entries : 500000 : Total Size= 11008137 bytes File Size = 805135 * *Baskets : 67 : Basket Size= 2821632 bytes Compression= 13.67 * *............................................................................* *Br 39 :channels.integral_max : Double_t integral_max[channels_] * *Entries : 500000 : Total Size= 14010002 bytes File Size = 742669 * *Baskets : 81 : Basket Size= 3590656 bytes Compression= 18.86 * *............................................................................*

I tried this, but it doesn’t work.

TFile* file = new TFile(fileName, "READ");
TTree* tree = (TTree*)file->Get("Events");
	
Long64_t nentries = tree->GetEntries();
cout<<"The tree contains "<<nentries<<" entries"<<endl;
	
std::vector<float> *regions[channels_] = 0;
tree->SetBranchAddress("vector<float>",&regions[channels_]);

TH1F* h_source = new TH1F("h_source", "Spectrum", 300, 0, 40000);
	
	for(Long64_t entry = 0; entry < nentries; entry++) {
		tree->GetEntry(entry);
		if(regions[channels_] > 0) {
			h_source->Fill(regions[channels_];
		}
	}
tree->Print();
	
TCanvas* c1 = new TCanvas();
h_source->Draw();

Probably is an easy question and I’ve done a mess, but I’m at the beginning with Root and furthermore I don’t speak english very well.

Thanks

2

Hi,

because I don’t know how set the address of the branch with a vector

Actually this is more complex than that since this vector is itself held in a collection (The ‘channels’).

tree->SetBranchAddress(“vector”,&regions[channels_]);

The 1st parameter is supposed to be the name of the branch (“channels.regions” in your case). The 2nd parameter does not have the right type (and the right type would be hard to create).

Instead I recommend you use the TTreeReader or the result of TTree::MakeProxy (or even the result of TFile::MakeProject and/or you own library containing the code for the class containing the channels).

Cheers,
Philippe.

3