Hi,
> is there some way I can detect nan
You can use TMath::IsNan ... but that's not really you problem.
> tt->FindLeaf("jetdata.ijet_phi")->GetValue(1431)
Is resquesting the 1431th value of the variable in jetdata.ijet_phi in the
CURRENT event (which is unlikely to be #1431). This should only be used
for variable that are arrays (which an event). To access a single value
of jetdata.ijet_phi in the event #1431, you do something more like:
tt->GetEntry(1431);
tt->FindLeaf("jetdata.ijet_phi")->GetValue(0);
[The code could actually be sped-up by just reading one branch but that's
another story].
I recommend (re)reading the chapter on TTree in the User's Guide.
Cheers,
Philippe.
-----Original Message-----
From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of mbrustke@purdue.edu
Sent: Wednesday, July 09, 2003 3:24 PM
To: roottalk@pcroot.cern.ch
Subject: [ROOT] NAN in NTuples
I've read about some similar problems in the digest, but most of them seemed
to
involve histogramming, while mine simply involves accessing the values of
leaves of a tree. I setup a tree using the following syntax:
afile = new TFile("mc.root")
TTree *tt = afile.Get("t")
Unfortunately, my MC files are around 60 megs each, so I can't attach one.
I
am working on creating a smaller file with a few good events and one or two
bad
ones, but I'm still a novice with root. The problem happens with different
instances of different variables, but the first one on which I noticed it
was
event #1431 of a variable called jetdata.ijet_phi. When I call
tt->Scan("jetdata.ijet_phi")
all values display properly, but if I call
tt->FindLeaf("jetdata.ijet_phi")->GetValue(1431)
I get:
Error: Symbol nan is not defined in current scope FILE: LINE:0
(const Double_t)nan
*** Interpreter error recovered ***
I have experienced this under versions 3.03/07, 3.03/09, and 3.05/03., all
under various versions of Linux. As I said, tt->Scan displays reasonable
looking values for the offending variables, and I can histogram them without
error, but accessing certain ones individually results in nan. Even if
there
is no way to fix this, is there some way I can detect nan entries and simply
skip them when I am looping over the entire dataset?
Thanks,
Max Brustkern
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