Hi,
I’m using root v6.12/06 and have been trying to take a large TTree in a data file (~1.8 GB) that needs to have some of its data altered, and then add an index to the resulting tree. I have used the following code to do so:
void CleanUpLib() {
TFile *fin = new TFile("inputdata.root");
TTree *pltree = (TTree*)fin->Get("pmtresponse/PhotonLibraryData");
int Voxel; pltree->SetBranchAddress("Voxel", &Voxel);
int OpChannel; pltree->SetBranchAddress("OpChannel", &OpChannel);
Float_t Visibility; pltree->SetBranchAddress("Visibility", &Visibility);
Float_t ReflVisibility; pltree->SetBranchAddress("ReflVisibility", &ReflVisibility);
Float_t ReflTfirst; pltree->SetBranchAddress("ReflTfirst", &ReflTfirst);
//-----
TFile *fout = new TFile("data_cleaned.root","RECREATE");
TTree *cltree = new TTree("PhotonLibraryData", "PhotonLibraryData");
int cVoxel; cltree->Branch("Voxel", &cVoxel, "Voxel/I");
int cOpChannel; cltree->Branch("OpChannel", &cOpChannel, "OpChannel/I");
Float_t cVisibility; cltree->Branch("Visibility", &cVisibility, "Visibility/F");
Float_t cReflVisibility; cltree->Branch("ReflVisibility", &cReflVisibility,"ReflVisibility/F");
Float_t cReflTfirst; cltree->Branch("ReflTfirst", &cReflTfirst, "ReflTfirst/F");
//-----
// COPY ALL BUT ONE OF THE DUPLICATE SETS TO THE NEW TREE cltree
const int TotNum = pltree->GetEntries();
for (int V = 0; V < TotNum; V++) {
if (V>=160142198 && V<=160201637) {
// SKIP THESE ENTRIES BECAUSE REASONS
continue;
}
//COPY ELEMENTS TO NEW TREE
pltree->GetEntry(V);
cVoxel = Voxel;
cOpChannel = OpChannel;
cVisibility = Visibility;
cReflVisibility = ReflVisibility;
cReflTfirst = ReflTfirst;
cltree->Fill();
}
delete fin;
// BUILD INDEX AND WRITE TO FILE
int cTotNum = cltree->GetEntries();
cltree->SetEstimate(cTotNum);
cltree->BuildIndex("Voxel","OpChannel");
cltree->Print();
fout->cd();
cltree->Write();
delete fout;
}
Without the BuildIndex() line, the code runs as expected. However, when BuildIndex() is included once the code gets to the Write() line I get two Error in <TBufferFile::WriteByteCount>: bytecount too large (more than 1073741822) errors followed by a segmentation violation. The new file does in fact exist regardless of these errors, though it doesn’t contain the index.
I know from reading other forum posts that this is probably happening due to me saving more than 1GB of data in a single buffer. How do I successfully get the index written to file without this error, and why is it the index that’s causing the problem?
Any help would be greatly appreciated!