I am trying to write a tree with some branches.
e.g of how I am defining a branch:
myTree->Branch(“pt”,&pt,“pt/D”);
I want one of them to be filled only under certain conditions.
So I do myTree->SetBranchStatus(“pt”,0) whenever that condition is false and I set the status to 1 whenever the condition is true and then I do
myTree->Fill();
I have seen that even if the status of this branch is set to 0, if I print
the values of the local tree variable i.e. cout<<pt<<endl;
it gives some values.When I saw the plot, I found that those values(when the brstatus is 0) are filled inside it.
What is it that I am missing?
Could someone help me?
I have another query:
If I check the Entries of this branch from the plot, then do
I expect it to be equal to the number of times its status is set to 1
or the number of times myTree->Fill() is executed?
Thanks for any suggestions,
Best Regards,
Shilpi Jain
[quote]What is it that I am missing? [/quote]The BranchStatus concerns only reading back.
When filling, all branches must be equalling filled otherwise you are losing the synchronization of the branches. (I.e. if your attempt had succeeded, you would have lost all possibility of correlating correctly the pt with the other branches (event by event)).
The only way to have an optional branch is to use a container (array, vector, etc). For example you could use
vector<double> ptarr;
myTree->Branch("pt",&ptarr)
....
loop over events
ptarr.clear();
if (!condition) {
ptarr.push_back(ptvalue);
}
myTree->Fill();
}
vector<double> ptarr;
myTree->Branch("pt","std::vector<double>",&ptarr)
for(int ievent = 0; ievent<nevent;ievent++)
{
ptarr.clear();
if (!condition) {
ptarr.push_back(ptvalue);
} //end of if
myTree->Fill();
} //end of for
but its giving the problem of segmentation violation whenever myTree->Fill() is executed.
Also,
Somehow myTree->Branch(“pt”,&ptarr) is not working! I tried compiling this on lxplus
but it didn’t compile. It gave an error like :
===============ERROR==============================================
error: invalid conversion from std::vector<double, std::allocator<double> >*' toInt_t’
error: initializing argument 2 of `virtual Int_t TTree::Branch(const char*, Int_t, Int_t)’
vector<double> ptarr;
myTree->Branch("pt","std::vector<double>",&ptarr)
for(int ievent = 0; ievent<nevent;ievent++)
{
ptarr.clear();
if (!condition) {
ptarr.push_back(ptvalue);
} //end of if
myTree->Fill();
} //end of for
but its giving the problem of segmentation violation whenever myTree->Fill() is executed.
Also,
Somehow myTree->Branch(“pt”,&ptarr) is not working! I tried compiling this on lxplus
but it didn’t compile. It gave an error like :
===============ERROR==============================================
error: invalid conversion from std::vector<double, std::allocator<double> >*' toInt_t’
error: initializing argument 2 of `virtual Int_t TTree::Branch(const char*, Int_t, Int_t)’
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