Re: GetValue for TLeafF and TLeafI with variable-sized arrays

Hi Philip,

Thanks for reporting this problem. All the TLeaf classes have been updated (revision 30076) with the missing code (that was present only in TLeafI).

Cheers,
Philippe.

Philip Rodrigues wrote:
> Hi roottalk,
> I'm trying to access the values of variable-sized arrays using
> TLeaf::GetValue, with code like the following:
>
> TTree* t = [[ some tree ]];
> // branch "dir" has title "dir[nring][3]/F"
> // where "nring" has type "nring/I"
> TBranch* b_dir=t->FindBranch("dir");
> TLeaf* l_dir=t->FindLeaf("dir");
>
> dir->GetEntry(0);
> // Should get dir[0][1] in the 0th entry
> l_dir->GetValue(1);
>
> I noticed that this fails for "dir", which is a float variable, but
> succeeds for integer variables. I found the necessary workaround,
> which is to do:
>
> l_dir->GetLeafCount()->GetBranch()->GetEntry(0);
>
> before dir->GetEntry(0), but I'm wondering if I'm misunderstanding how
> this is supposed to work. Should it be necessary to put this extra
> line in?
>
> Thanks,
> Philip
>
> PS The reason it *does* work for integer variables is because
> TLeafI::ReadBasket looks like:
>
> if (!fLeafCount && fNdata == 1) {
> b >> fValue[0];
> } else {
> if (fLeafCount) {
> /**/ Long64_t entry = fBranch->GetReadEntry();
> /**/ if (fLeafCount->GetBranch()->GetReadEntry() != entry) {
> /**/ fLeafCount->GetBranch()->GetEntry(entry);
> /**/ }
> Int_t len = Int_t(fLeafCount->GetValue());
> if (len > fLeafCount->GetMaximum()) {
> printf("ERROR leaf:%s, len=%d and
> max=%d\n",GetName(),len,fLeafCount->GetMaximum());
> len = fLeafCount->GetMaximum();
> }
> [ ... ]
>
> so it does the GetEntry on the necessary branch. The corresponding
> function in TLeafF lacks the lines I've marked with a /**/
>
Received on Wed Sep 09 2009 - 02:35:23 CEST