Can't get TTree from file located on CASTOR

ROOT
1

Hello all,

Could someone please help with my problem?

I’m trying to read ROOT file located on CASTOR:

[kskovpen@lxplus232]~/work/testarea/15.6.5.5/PhysicsAnalysis/AnalysisCommon/UserAnalysis/run/proc% root
root [0] f=TFile::Open(“rfio:/castor/cern.ch/user/k/kskovpen/data09_900GeV.root”);
root [1] TTree tr = (TTree)f->Get(“rfio:/castor/cern.ch/user/k/kskovpen/data09_900GeV.root:/StudyElectrons/elec_1”);
root [2] tr->GetName();
Error: illegal pointer to class object tr 0x0 2522 (tmpfile):1:
*** Interpreter error recovered ***
root [3]

So, the pointer is NULL… It’s quite strange because this TTree was properly filled. Maybe I’m doing something completely wrong here?

Thank you in advance,

Kirill

2

Hi,

I’m surprised that you would have to state the filename again when extracting the tree from the file - but then again I’ve never used castor… Anyway, try that:

TTree tr = (TTree)f->Get(“StudyElectrons/elec_1”);

Cheers, Axel.

3

Hi Axel!

Thanks again for the help! It worked! Though it’s still interesting why it is not working if given the whole link to TTree…

Thanks,

Kirill

4

[quote]Though it’s still interesting why it is not working if given the whole link to TTree… [/quote]The function TFile::Get expects a name relative to the file it is being called on ; In the general case supporting the syntax as you expected it would require TFile::Get to open yet another TFile object hence effectively executing an action on a TFile object different from the one you explicitly requested the action to be executed on … leading to confusion …

Philippe.

5

Thank you! All clear!