Hi Rene!
On Oct 14, 2004, at 7:31 PM, Rene Brun wrote:
> Roland,
>
> A TChain is a TTree. So everything working on TTree should also
> work with TChain.
>
My question was more aimed at when I have to call special stuff to
ensure that after a new TTree has been loaded, everything continues to
work. Is manager->UpdateFormulaLeaves() in ::Notify() enough?
> Rene Brun
>
> On Thu, 14
> Oct 2004, Roland Kuhn wrote:
>
>> Hi Rene!
>>
>> On Oct 13, 2004, at 8:54 AM, Rene Brun wrote:
>>
>>> Hi Roland,
>>>
>>> I agree with your comments about TTreeFormula.
>>> This class is a key element of TTree::Draw, but it can also be used
>>> independently.
>>> It requires a much better documentation.
>>>
>> I tried to understand what's going on, and I must admit that I didn't
>> really have enough brain memory to get a complete picture (at least
>> not
>> in a reasonable timeframe). From what I've seen TTreeFormula is always
>> managed by a TTreeFormulaManager. I have already found out that the
>> main use of this class is to manage the (up to four) expressions in
>> the
>> varexp of TTree::Draw plus the selection criterion, but from the code
>> it is not immediately clear to me what the semantics are. What do I
>> need to get it working reliably with a TChain?
>>
>> I'm currently looping with a custom MakeClass-generated class, filling
>> my own arbirarily dimensioned histograms. Now I want to include a cut
>> criterion, which should be parsed like a selection to TTree::Draw. I
>> figure I need something a la
>>
>> in constructor:
>> manager=new TTreeFormulaManager;
>>
>> in Loop():
>> cut=new TTreeFormula("some_name",cut,tree);
>> manager->Add(cut);
>> manager->Sync();
>> for(;;) {
>> ii=LoadTree(i);
>> fChain->GetEntry(ii);
>> Double_t cut_result=cut->EvalInstance();
>> ...
>> }
>> manager->Remove(cut);
>> manager->Sync();
>>
>> I suppose I should also add manager->UpdateFormulaLeaves() to my
>> ::Notify(), right? Is there something else which is needed?
>>
>> Thanks very much for your help!
>>
>> Ciao,
>> Roland
>>
>> --
>> TU Muenchen, Physik-Department E18, James-Franck-Str. 85747 Garching
>> Telefon 089/289-12592; Telefax 089/289-12570
>> --
>> A mouse is a device used to point at
>> the xterm you want to type in.
>> Kim Alm on a.s.r.
>>
>
>
Ciao,
Roland
--
TU Muenchen, Physik-Department E18, James-Franck-Str. 85747 Garching
Telefon 089/289-12592; Telefax 089/289-12570
--
A mouse is a device used to point at
the xterm you want to type in.
Kim Alm on a.s.r.
This archive was generated by hypermail 2b29 : Sun Jan 02 2005 - 05:50:10 MET