Re: (no subject)

Dmitry,

When you do
root [5] t2->GetBranch("fEvent")->GetEntries() you get 1 entry. So it is normal that
root [4] t->GetBranch("fEvent")->GetEntry(0)

   (Int_t)425
   root [5] t->GetBranch("fEvent")->GetEntry(1)    (Int_t)0
The last command must return 0, since you only have one entry.

Rene

On Thu, 24 Nov
2005, Dmitry
Naumov wrote:

> Sorry, I forgot to mention that I first tried what you suggested and it did
> not work (By the way
> why it should work if the tree can have in principle different branches each
> having
> different number of events? What does it mean "Entries" in this case?)
> Thus I though that you probably meant setting number of events in the given
> branch.
> Just a check of your first message:
>
> root [0] TChain *t = new TChain("nuclon")
> root [1] t->AddFile("t1.root")
> (Int_t)1
> root [2] t->AddFile("t2.root")
> (Int_t)1
> root [3] t->SetEntries(2)
> (Long64_t)2
> root [4] t->GetBranch("fEvent")->GetEntry(0)
> (Int_t)425
> root [5] t->GetBranch("fEvent")->GetEntry(1)
> (Int_t)0
>
>
> Just a check that each event has its 1 event:
> root [0] TFile f1("t1.root")
> root [1] TTree *t1 = (TTree*)f1.Get("nuclon")
> root [2] t1->GetBranch("fEvent")->GetEntries()
> (const Long64_t)1
> root [3] TFile f2("t2.root")
> root [4] TTree *t2 = (TTree*)f2.Get("nuclon")
> root [5] t2->GetBranch("fEvent")->GetEntries()
> (const Long64_t)1
>
> Rene Brun wrote:
>
>> You did not read my mail correctly. I told you to do
>> t->SetEntries(nentries);
>> and not
>> t->GetBranch("fEvent")->SetEntries*();
>>
>> Rene Brun
>>
>> On Thu, 24 Nov 2005, Dmitry Naumov wrote:
>>
>>> Dear Rene,
>>>
>>> thank you for this advice. I tried it but it does not read anyway the
>>> second event:
>>>
>>> root [0] TChain *t = new TChain("nuclon")
>>> root [1] t->AddFile("t1.root")
>>> (Int_t)1
>>> root [2] t->AddFile("t2.root")
>>> (Int_t)1
>>> root [3] t->GetBranch("fEvent")->SetEntries(2)
>>> root [4] t->GetBranch("fEvent")->GetEntries() // to check!
>>> (const Long64_t)2
>>> root [5] t->GetBranch("fEvent")->GetEntry(0)
>>> (Int_t)425 // OK
>>> root [6] t->GetBranch("fEvent")->GetEntry(1)
>>> (Int_t)0 // empty ?!
>>>
>>> root Version 5.02/00 Dmitry
>>>
>>> Rene Brun wrote:
>>>
>>>> Dmitry,
>>>>
>>>> Call t->SetEntries(nentries);
>>>> where nentries is the number of entries if your branches.
>>>>
>>>> Rene Brun
>>>>
>>>> On Thu, 24 Nov 2005, Dmitry Naumov wrote:
>>>>
>>>>> Dear rooters,
>>>>>
>>>>> I have a strange problem:
>>>>> I create TTree with two branches: fRunPars and fEvent.
>>>>> fRunPars is filled only once and it containes simulation settings
>>>>> fEvent s filled for each event:
>>>>>
>>>>> fTree->GetBranch("fEvent")->Fill()
>>>>>
>>>>> Now I created a set of files with these trees. I want to make a TChain
>>>>> of them:
>>>>> TChain *t = new TChain("nuclon");
>>>>> t->AddFile("t1.root"); // has 1 event
>>>>> t->AddFile("t2.root"); // has 1 event
>>>>> t->GetEntries(); // gives 0. It is OK because TTree
>>>>> // has two branches one of which
>>>>> is filled
>>>>> // many times, another only once,
>>>>> thus Entries probably has no sense
>>>>> t->GetBranch("fEvent")->GetEntries(); // gives 1 ?! Why not 2?
>>>>>
>>>>> If I do
>>>>> t->GetBranch("fEvent")->GetEntry(0); // it is OK
>>>>> t->GetBranch("fEvent")->GetEntry(1); // this event is empty.
>>>>>
>>>>>
>>>>> Do I misunderstand something? Many thanks in advance, Dmitry
>>>>>
>>>
>
Received on Thu Nov 24 2005 - 17:45:19 MET