Re: TEntryList for TChain

I do not understand your mail. I was precisely telling you to use a TEventList. see my example again.

Rene

Hovhannes Khandanyan wrote:
>
> Hello Rene,
>
> I tried the prescription that you recommended but it had the same
> problem. Anyhow, when I tried using TEventList instead of TEntryList
> that worked ! Maybe I have to somehow additionally instruct the
> TChain to go to the specific tree? If so that presumably is an extra
> complication when using TEntryList wrt TEventList.
>
> Thanks,
> Hovhannes
>
>
>
> On Jun 23, 2010, at 10:28 AM, Rene Brun wrote:
>
>> I see that there is a missing function in TEntryList to loop the way
>> you intend to do it.
>> So,instead of:
>>
>> CollectionTree->Draw(">>seltrackevents",cut,"entrylist");
>> TEntryList *seltrackevents =
>> (TEntryList*)gDirectory->Get("seltrackevents");
>>
>> Int_t jj = -1;
>> seltrackevents->GetEntry(0);
>> do {
>>
>> jj = seltrackevents->Next();
>> cout << "jj = " << jj << endl;
>>
>> CollectionTree->GetEntry(jj);
>> //
>> .....
>> .......
>>
>> } while(jj != -1);
>>
>> I suggest to do:
>>
>> CollectionTree->Draw(">>seltrackevents",cut);
>> TEventList *seltrackevents =
>> (TEventList*)gDirectory->Get("seltrackevents");
>>
>> int nentries = seltrackevents->GetN();
>> for (int jj = 0;jj<nentries;jj++) {
>> Long64_t entry = seltrackevents->GetEntry(jj);
>> cout << "jj = " << jj <<" entry= " <<entry << endl;
>>
>> CollectionTree->GetEntry(entry);
>> //
>> .....
>> .......
>> }
>>
>>
>> Rene Brun
>>
>>
>>
>> Hovhannes Khandanyan wrote:
>>>
>>> Dear ROOTers,
>>>
>>> I have a chain of ROOT trees:
>>>
>>> TChain* CollectionTree = new TChain("CollectionTree");
>>> CollectionTree->Add("many files *.root");
>>>
>>> for which I create an entrylist
>>>
>>> CollectionTree->Draw(">>seltrackevents",cut,"entrylist");
>>> TEntryList *seltrackevents =
>>> (TEntryList*)gDirectory->Get("seltrackevents");
>>>
>>> Then I try to look through my entrylist in the following way:
>>>
>>> Int_t jj = -1;
>>> seltrackevents->GetEntry(0);
>>> do {
>>>
>>> jj = seltrackevents->Next();
>>> cout << "jj = " << jj << endl;
>>>
>>> CollectionTree->GetEntry(jj);
>>> //
>>> .....
>>> .......
>>>
>>> } while(jj != -1);
>>>
>>> This works correctly only for the 1st file of the chain, since jj is
>>> always the event number within the given file 'local event number'
>>> as opposed 'global event number' for the whole chain. Please let me
>>> know what I should use instead/on top of jj =
>>> seltrackevents->Next(); to make sure that I get the event from the
>>> correct chain file.
>>>
>>> Thanks for any help,
>>> Hovhannes
>>>
>>
>
Received on Wed Jun 23 2010 - 12:13:16 CEST