Thanks for the help, I managed to modify my program so that it now uses chains. However, I still encounter a proplem when trying to copy the subset of a (chain) tree into a new file.
Though the program runs without a problem and writes the subset of the tree to the output file “simdata” the content of “RunID” and “EventID” are corrupted (yield segmentation violation when trying to draw in root).
I suspect the reason to be that I use two chains on the same tree though I thought that using the clone command when doing the dummy-SetTree() would separat them in memory.
Below is an an excerpt of my program:
class TreeEvtSelection
{
public:
TreeEvtSelection()
: fChain(0),
fNewTree(0),
fTreeNumber(0),
fRunID(0),
fEvtID(0),
fEntry(0)
{};
~TreeEvtSelection() {};
void SetTree(TChain* chain) {
fChain = chain;
fNewTree = fChain->CloneTree(0);
fChain->SetBranchAddress("RunID",&fRunID);
fChain->SetBranchAddress("EventID",&fEvtID);
};
void SelectEvt(int treeNumber, int evtID, int newRunID, int newEvtID) {
for ( int entryID=fEntry; entryID<fChain->GetEntries(); entryID++ ){
fChain->GetEntry(entryID);
fTreeNumber = fChain->GetTreeNumber();
if ( fTreeNumber == treeNumber && fEvtID == evtID ) {
fEvtID = newEvtID;
fNewTree->Fill();
fEntry = entryID+1;
break;
} else if ( (fTreeNumber == treeNumber && fEvtID > evtID) ||
fTreeNumber > treeNumber ) {
fEntry = entryID;
break;
}
}
};
main program:
TFile* simDataFile = new TFile("simDataFile.root","RECREATE");
*** this is a loop over the different input file names
treeChain2->Add(fileName.c_str());
treeChain->Add(fileName.c_str());
***
simDataFile->cd();
TreeEvtSelection* dummy = new TreeEvtSelection;
dummy->SetTree((TChain*) treeChain2->Clone());
*** I forgot these lines the first time
int evtID;
int maxEntries = treeChain->GetEntries();
treeChain->SetBranchAddress("EventID",&evtID);
***
for ( int entry=0; entry<maxEntries; entry++ ) {
treeChain->GetEntry(entry);
int treeNumber = treeChain->GetTreeNumber();
if (selection) {
dummy->SelectEvt(treeNumber,evtID,newRunID,newEvtID);
}
}
dummy->Save();
***
thanks for the hint. Unfortunately, it doesn’t work.
Also, I just noticed that I forgot a crucial part in the main program (the 2 lines before the FOR loop below). Actually, I think it is these lines that cause the trouble as they define a second time a pointer to “EventID”, though I thought using the Clone method (treeChain2->Clone()) would solve this.
main program:
TFile* simDataFile = new TFile("simDataFile.root","RECREATE");
*** this is a loop over the different input file names
treeChain2->Add(fileName.c_str());
treeChain->Add(fileName.c_str());
***
simDataFile->cd();
TreeEvtSelection* dummy = new TreeEvtSelection;
dummy->SetTree((TChain*) treeChain2->Clone());
int maxEntries = treeChain->GetEntries();
treeChain->SetBranchAddress("EventID",&evtID);
for ( int entry=0; entry<maxEntries; entry++ ) {
treeChain->GetEntry(entry);
int treeNumber = treeChain->GetTreeNumber();
if (selection) {
dummy->SelectEvt(treeNumber,evtID,newRunID,newEvtID);
}
}
dummy->Save();
***
I am a bit confused on what you are trying to do …
What’s the difference between treeChain and treeChain2?
Why do you completely clone (including data) one of the chain and then turn around and clone it again. [ treeChain2->Clone() completely clone the chain ]. In addition the cast code treeChain2->Clone() [/code] is illegal since the object returned by Clone is really a TTree.
would produce two completely independent chains in memory which I think I need in order to use the two SetBranchAddresses independently from each other.
From what you write I understand that this is indeed the case and the second clone command is unnecessary and even illegal. However, also using “dummy->SetTree(treeChain2)” doesn’t solve the problem.
[quote]the content of “RunID” and “EventID” are corrupted (yield segmentation violation when trying to draw in root). [/quote]Humm this is very bad … and there is no clear reason in your code why this would be … My best guess is that the TTree (or TChain) you use to Draw is incorrect (has already been deleted or whatever else).
Anyway, your best bet is to send a complete, running example via an attached tar file so that we can reproduce the problem.
Actually, the drawing is done afterwards from the written file using TBrowser.
I also just looked at the value of fEvtID right before “fNewTree->Fill()” in “SelectEvt”; it has the correct values. What exactly happens when doing “fNewTree->Fill()”?
I will try to set up a running example but it may take a while as the program uses some non-standard libraries.
… and there is no clear reason in your code why this would be … My best guess is that the TTree (or TChain) you use to Draw is incorrect (has already been deleted or whatever else).