>As point out by Pasha:
> tv__tree->SetBranchAddress("_1.nhitcot",&nhitcot2);
> will work.
Oups I spoke a little to fast. It will NOT work.
You actually need to define a struct containing the full
content of the branch (which has the odd name "_1") by doing
something like:
class mystruct {
public:
int alg;
int charge;
float d0;
float eta;
int event;
int nhitax;
int nhitcot;
int nhitsil;
int nhitsilphi;
int nhitsilst;
int nhitsilz;
int nhitst;
float pT;
int paralg;
float phi0;
int run;
int trknum;
float z0;
}
mystruct object;
tv__tree->SetBranchAddress("_1",&object);
However, you might actually benefit from taking a look
at ROOT's MakeSelector facility or at D0's SEED facility
(http://www-d0.fnal.gov/nikhef/?seed).
Cheers,
Philippe.
-----Original Message-----
From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Anne-Sylvie
Nicollerat
Sent: Tuesday, November 20, 2001 4:49 PM
To: roottalk@pcroot.cern.ch
Subject: [ROOT] reading from trees once more
Hello !
I am trying to read the variables from a tree (named Tracks), using the
following macro (that I start after having started the tree viewer):
{
tv__tree = (TTree *) gROOT->FindObject("Tracks");
tv__tree_list->Add(tv__tree);
Int_t nhitcot2;
Int_t nhitax2;
Int_t nhitst2;
tv__tree->SetBranchAddress("nhitcot",&nhitcot2);
tv__tree->SetBranchAddress("nhitax",&nhitax2);
tv__tree->SetBranchAddress("nhitst",&nhitst2);
....
}
Then root returns me the following error message :
Error in <TTree::SetBranchAddress>: unknown branch -> nhitcot
Error in <TTree::SetBranchAddress>: unknown branch -> nhitax
Error in <TTree::SetBranchAddress>: unknown branch -> nhitst
When I look in the contents of my tree, doing tv__tree->Print(), I get
the following:
root [1] tv__tree->Print()
******************************************************************************
*Tree :Tracks :
Tracks *
*Entries : 48820 : Total = 3536541 bytes File Size =
3536541 *
* : : Tree compression factor =
1.00 *
******************************************************************************
*Br 0 :_1 :
alg/I:charge/I:d0/F:eta/F:event/I:nhitax/I:nhitcot/I: *
* |
nhitsil/I:nhitsilphi/I:nhitsilst/I:nhitsilz/I:nhitst/I:pT/F: *
* |
paralg/I:phi0/F:run/I:trknum/I:z0/F *
*Entries : 48820 : Total Size= 3515490 bytes File Size =
3515490 *
*Baskets : 110 : Basket Size= 32000 bytes Compression=
1.00 *
I think the suspicious thing is the 0:_1 thing. It look as the variables
are not directly accessible. Actually when I try to access the tree
variables from the browser, I first come to a _1 leave that I have to
open to access the tree variables.
Just another thing: I can for instance plot an histogram directly from
the viewer and then root executes the following command :
tv__tree->Draw("_1.nhitcot","","hist", 48820, 0);
Do you know how I could acces the arguments of the tree in my macro ?
Thanks a lot
Anne-Sylvie
--
-----------------------------------
Anne-Sylvie Nicollerat
office 327-52-56, phone 1-630-840-3899
Fermilab/CDF MS 223 PO box 500,
Batavia, IL 60510 USA
"Pour le croyant Dieu se trouve au debut, pour le physicien au terme de toute pensee." (Planck)
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