Re: weight in TH1F from Tree

From: Jean-Eric Campagne <campagne_at_lal.in2p3.fr>
Date: Fri, 20 May 2005 16:04:39 +0200

Rene,
The very first example may be well replaced by the "two lines" of Root as it is just to read a very simple ascii file, don't you think? Regards
J.E

--On vendredi 20 mai 2005 15:57 +0200 Rene Brun <brun_at_pcroot.cern.ch> wrote:

> Hi Jean-Eric,
>
> For real beginners, I have added a new tutorial "basic2.C" in CVS head.
> It is a variant of the existing short tutorial basic.C showing how to
> create a tree from an ascii file.
>
> Could you give more details about the examples described in the manual
> that you find "ugly" and desperating?
>
> We are relectant to add either trivial or too complex information
> in a Users Guide that is already pretty big. However, I agree that
> showing simple examples is always good for people starting with
> the system. Our original expectation was that users will also
> look in the numerous tutorials provided in the standard distribution.
>
> Rene Brun
>
>
> On Fri, 20 May 2005, Jean-Eric Campagne wrote:
>
>> Thanks Rene.
>>
>> May I suggest you to put on the manual, the very simple TTree creation
>> following lines
>> TTree T2("t2","Flux Opt Pi-");
>>
>> T2.ReadFile("sploptiminus130.dat","sene/F:snue:snumu:snutau:sanue:sanumu
>> :sanutau"); you have suggested to me in one of your previous mails. I
>> know many people that this kind of things will help very much... The
>> examples described in the manual are a little bit urgly and desperate
>> some well PAW experienced people...
>>
>> Best W.
>> J.E
>>
>>
>>
>> --On vendredi 20 mai 2005 12:26 +0200 Rene Brun <brun_at_pcroot.cern.ch>
>> wrote:
>>
>>> Hi Jean-Eric,
>>>
>>> When you need to include a C++ variable in one of the
>>> expressions of TTree::Draw use the Form function (defined in TString)
>>> eg
>>>
>>> const double SCALE = 0.3464e-12/1.e-6;
>>> T3.Draw("sene>>h222(501,0.01604,2.00396)",
>>> Form("snumu*%g*(sene<1.5)",SCALE));
>>>
>>> Rene Brun
>>>
>>> On Fri, 20 May 2005, Jean-Eric Campagne wrote:
>>>
>>>> Dear developpers,
>>>>
>>>> Imagine that I have a simple tree (T3) with "sene" and "snumu" as
>>>> variable. I would like to produce a 1D histo with "sene" weighted by
>>>> "snumu". Up to now there is no problem.
>>>> Now, I would like to rescale the weight with a SCALE factor, I have
>>>> tried
>>>>
>>>> const double SCALE = 0.3464e-12/1.e-6; //To rescale Old Flux format to
>>>> Opti Flux
>>>> T3.Draw("sene>>h222(501,0.01604,2.00396)","snumu*SCALE*(sene<1.5)");
>>>>
>>>> But ROOT give me this error message:
>>>>
>>>> *ERROR 30 :
>>>> Bad numerical expression : "SCALE"
>>>>
>>>> what can I do?
>>>>
>>>> NB: I have not done snumu%sene has I would like to impose the binning
>>>> via the histo definition...
>>>>
>>>>
>>>> ......................................................................
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>>>>
>>
>>
>>
>> ........................................................................
>> ... .LAL - IN2P3 - CNRS
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>> .Piece 108
>> .Tel +33 (0)1 64 46 84 29
>> .Fax +33 (0)1 64 46 83 97
>> ........................................................................
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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

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Received on Fri May 20 2005 - 16:04:46 MEST