Hi Rene,
Thanks for your speedy reply. In fact EventNum has no relation to the
TTree event entry number, it's just an "event identifier" in that
tree1-Scan() produces something like:
*************************************
* Row * EventNum * X * Y * Z *
*************************************
* 0 * 3* 0.2* 0.4* 0.1*
* 1 * 7* 0.6* 0.1* 0.4*
* 2 * 9* 0.3* 0.2* 0.6*
etc
and I'd like to select EventNum == 3,7,9 in tree2. HOWEVER, I noticed
from a similar posting today by Stilianos that my code snippet below works if I
replace sprintf(myString,"\"EventNum == %d \"",EventNum) with
sprintf(myString,"EventNum == %d",EventNum), though I'm not quite sure
why! The problem is that it takes a long time to scan tree1 and create the
TEventList. I'll check out TTree::BuildIndex.
Thanks,
Mike.
On Tue, 24 Feb 2004, Rene Brun wrote:
> Hi Mike,
>
> To answer your question, I must know the relationship between
> your variable "EventNum" and the TTree entry number
> in your two Trees. Solutions to this kind of problem are typically
> using TEventList or TTree::BuildIndex
>
> Rene Brun
>
> On Tue, 24
> Feb 2004, Mike Carson wrote:
>
> >
> > Dear Rooters,
> >
> > I've got two TTrees, tree1 and tree2, with the same variable list
> > (EventNum X Y Z). I'd like to select those events in tree2 which have the
> > same EventNum as the events in tree1. I can do this with a couple of for
> > loops but it takes too long. I also tried this:
> >
> > Int_t numberOfEvents = tree1->GetEntries();
> > Char_t myString[20];
> >
> > for (Int_t i=0; i<numberOfEvents; i++) {
> > tree1->GetEvent(i);
> > sprintf(myString,"\"EventNum == %d \"",EventNum);
> > tree2->Draw(">>+eventList",myString);
> > }
> >
> > but that didn't work. I tried a similar thing with a TCut object instead
> > of myString...didn't work either. Any ideas?
> >
> > I'm using root version 3.10/02, gcc 3.2.2, RH9.0.
> >
> > Many thanks,
> > Mike.
> >
>
>
--
---------------------------------------------------------------------------
Michael Carson tel: +44 (0)114 2223543
Dept. of Physics and Astronomy fax: +44 (0)114 2728079
University of Sheffield email: m.j.carson@sheffield.ac.uk
Hicks Building, Hounsfield Road web: www.shef.ac.uk/physics
Sheffield, S3 7RH
UK
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