You should structure your histograms in a hierarchy using
the built-in mechanism in Root (Class TDirectory/TFile).
The macro below is an example:
Rene Brun
{
// .........................macro dirs.C............................
// This macro illustrates how to create a hierarchy of directories
// in a Root file.
// 10 directories called plane0, plane1, plane9 are created.
// Each plane directory contains 200 histograms.
// The hierarchy can be browsed by the Root browser as shown below
// Root > TBrowser b;
// click on the left pane on one of the plane directories.
// this shows the list of all histograms in this directory.
// Double click on one histogram to draw it (left mouse button).
// Select different options with the right mouse button.
//
// Instead of using the browser, you can also do:
// Root > top->cd();
// Root > plane3->cd();
// Root > h3_90N->Draw();
gROOT->Reset();
// create a new Root file
TFile *top = new TFile("top.root","recreate");
// create a subdirectory "tof" in this file
TDirectory *cdtof = top->mkdir("tof");
cdtof->cd(); // make the "tof" directory the current directory
// create a new subdirectory for each plane
const Int_t nplanes = 10;
const Int_t ncounters = 100;
char dirname[50];
char hname[20];
char htitle[80];
for (Int_t i=0;i<nplanes;i++) {
sprintf(dirname,"plane%d",i);
TDirectory *cdplane = cdtof->mkdir(dirname);
cdplane->cd();
// create counter histograms
for (Int_t j=0;j<ncounters;j++) {
sprintf(hname,"h%d_%dN",i,j);
sprintf(htitle,"hist for counter:%d in plane:%d North",j,i);
TH1F *hn = new TH1F(hname,htitle,100,0,100);
sprintf(hname,"h%d_%dS",i,j);
sprintf(htitle,"hist for counter:%d in plane:%d South",j,i);
TH1F *hs = new TH1F(hname,htitle,100,0,100);
}
cdtof->cd(); // change current directory to top
}
// .. fill histograms
// save histogram hierarchy in the file
top->Write();
delete top;
}