Re: Draw ves Project

From: Jean-Eric Campagne <campagne_at_lal.in2p3.fr>
Date: Wed, 08 Jun 2005 14:17:15 +0200

Merci Rene, je voulais etre sure que j'utilisais correctement TTree->Project et Tree->Draw.
Cordialement
Jean-Eric

--On mercredi 8 juin 2005 13:21 +0200 Rene Brun <brun_at_pcroot.cern.ch> wrote:

> Jean-Eric,
>
> The automatic histogram produced by the first query has 100 channels
> ranging from 0 to 110. This explains the difference with your second
> histogram ranging from 0 to 100.
> In your first query, you can force the binning replacing the line
> tree->Draw("zp","(pdg==211)&&(zp<100)&&(0<zp)");
> by
> tree->Draw("zp>>hfirst(100,0,100)","(pdg==211)&&(zp<100)&&(0<zp)");
>
>
> Rene Brun
>
> On Wed, 8 Jun 2005, Jean-Eric Campagne wrote:
>
>> Cher Rene,
>>
>> I am using ROOT 4.04/02 31may05
>>
>> I have put on the Web <http://opera.web.lal.in2p3.fr/temporaire/>
>> the file Pb.tgz
>>
>> There are a pb.C macro and the (quite large) ROOT File with the TTree.
>>
>> Jean-Eric
>>
>>
>> --On mercredi 8 juin 2005 12:09 +0200 Rene Brun <brun_at_pcroot.cern.ch>
>> wrote:
>>
>>> Jean-Eric,
>>>
>>> I cannot reproduce this problem.
>>> Note that TTree::Project calls TTree::Draw. So, I do not see why the
>>> output should be different.
>>> Please:
>>> -tell us which version of ROOT?
>>> -send the shortest possible script with a file repducing your problem
>>>
>>> Rene Brun
>>>
>>> On Wed, 8 Jun 2005, Jean-Eric Campagne wrote:
>>>
>>>> Dear developpers
>>>>
>>>> I have done the following
>>>> 1) open a ROOT file with a TTree which contains "zp" and "pdg" as
>>>> variables 2) do the tree drawing
>>>> tree->Draw("zp","pdg==211")
>>>> Then just to show for student an other possibility
>>>> 3) create a TH1D* h1 with ("h1","z prod of pi+",100,0,100)
>>>> 4) project the tree on h1 as followed
>>>> tree->Project(h1->GetName(),"zp","pdg==211")
>>>> 5) draw the result
>>>> h1->Draw("SAME")
>>>>
>>>> To my great surprise the 2 plots does not fit each other (see pb.ps
>>>> attached), and this is not just bin to bin fluctuation
>>>> Have you an idea?
>>>> Regards
>>>> Jean-Eric
>>>>
>>>>
>>>> ......................................................................
>>>> .. ... .LAL - IN2P3 - CNRS
>>>> .LAL - B.P 34 - 91898 Orsay Cedex - France
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>>>> .. ...
>>>>
>>>>
>>
>>
>>
>> ........................................................................
>> ... .LAL - IN2P3 - CNRS
>> .LAL - B.P 34 - 91898 Orsay Cedex - France
>> .Piece 108
>> .Tel +33 (0)1 64 46 84 29
>> .Fax +33 (0)1 64 46 83 97
>> ........................................................................
>> ...
>>
>>

...........................................................................
.LAL - IN2P3 - CNRS
.LAL - B.P 34 - 91898 Orsay Cedex - France
.Piece 108
.Tel +33 (0)1 64 46 84 29

.Fax +33 (0)1 64 46 83 97

...........................................................................

Received on Wed Jun 08 2005 - 14:17:22 MEST