branch_sizes.C

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// branch_sizes.C: size on disk of the branches of the event tree per event, used for the data volume tables of the
// format documents. The size of a branch is calculated with sizeOnDisk() of macro/profiling/size/calculate_size.C
// for the whole file (only the tree header is read, so even large files are processed fast)
// example: root -b -q -l 'branch_sizes.C("bmnsim.root")' | grep -E '^(#|SIZE)' > digi/branch_sizes_sim.txt
R__ADD_INCLUDE_PATH($VMCWORKDIR)
#include "macro/profiling/size/calculate_size.C"
 
void branch_sizes(TString fileName, TString treeName = "bmndata")
{
    gSystem->ExpandPathName(fileName);
    TFile* file = TFile::Open(fileName);
    if (!file || file->IsZombie()) {
        cout << "ERROR: cannot open file " << fileName << endl;
        return;
    }
    TTree* tree = (TTree*)file->Get(treeName);
    if (!tree || tree->GetEntries() == 0) {
        cout << "ERROR: no tree " << treeName << " or no events in file " << fileName << endl;
        return;
    }
 
    Long64_t nEvents = tree->GetEntries();
    printf("# file %s, tree %s, %lld events\n", gSystem->BaseName(fileName), treeName.Data(), nEvents);
    TIter next(tree->GetListOfBranches());
    TBranch* branch;
    while ((branch = (TBranch*)next())) {
        // size of the branch together with its sub-branches
        printf("SIZE %-28s zip/ev=%10.1f B\n", branch->GetName(), (Double_t)sizeOnDisk(branch, true) / nEvents);
    }
}