Re: Re: Bug or feature?

From: Philippe Canal <pcanal_at_fnal.gov>
Date: Wed, 28 Jan 2009 17:04:34 -0600


 > which is ok I guess, but I don't need to do that for histograms and the need for casting is a bad interface.

GetObjectUnchecked is a low level interface, don't use it directly :) (... well unless you need to the 'Unchecked' behavior).

Instead use:

    TF1 *sigmaPar; A->GetObject("sigmaPar",sigmaPar);

sigmaPar will be zero if the object does not exist or is of the wrong type.

Cheers,
Philippe.

Arthur E. Snyder wrote:
> I find I can recover my funtcions by being very explicit:
>
> root [16] ((TF1*)A->GetObjectUnchecked("sigmaPar"))->Print()
> sigmaPar : pol4 Ndim= 1, Npar= 5, Noper= 1
> fExpr[0] = pol4 action = 130 action param = 401
> Optimized expression
> fExpr[0] = pol4 action = 130 action param = 401
> Par 0 #alpha_{0} = 0.00493591
> Par 1 #alpha_{1} = 0.0171368
> Par 2 #alpha_{2} = -0.00493408
> Par 3 #alpha_{3} = 0.00143038
> Par 4 #alpha_{4} = -0.000135192
> root [17] ((TF1*)B->GetObjectUnchecked("sigmaPar"))->Print()
> sigmaPar : pol4 Ndim= 1, Npar= 5, Noper= 1
> fExpr[0] = pol4 action = 130 action param = 401
> Optimized expression
> fExpr[0] = pol4 action = 130 action param = 401
> Par 0 #alpha_{0} = 0.00493591
> Par 1 #alpha_{1} = 0.0205642
> Par 2 #alpha_{2} = -0.00493408
> Par 3 #alpha_{3} = 0.00143038
> Par 4 #alpha_{4} = -0.000135192
>
> which is ok I guess, but I don't need to do that for histograms and
> the need for casting is a bad interface.
>
> -Art S.
>
>
> A.E. Snyder, Group EC \!c*p?/
> SLAC Mail Stop #95 ((. .))
> Box 4349 |
> Stanford, Ca, USA, 94309 '\|/`
> e-mail:snyder_at_slac.stanford.edu o
> phone:650-926-2701 _
> http://www.slac.stanford.edu/~snyder BaBar
> FAX:650-926-2657 Collaboration
>
>
>
> On Wed, 28 Jan 2009, Arthur E. Snyder wrote:
>
>>
>> Hello RootWorld:
>>
>> I'm having an odd problem saving TF1's in files. I have two versions
>> of the same function with the same name. I save them in two different
>> files, call them A and B. The functions differ only in the values
>> assigned the parameters.
>>
>> If I open file A, look at it (Draw or Print), then file B, I get the
>> function with the A-parameters. If I open in the other order I get
>> the B-paramters. If I cd to one of them, I still get function with
>> the parameters of the file 1st openned.
>>
>> This is completely unlike the behavoir of n-tuples or histograms
>> where if I open multiple files I get the one I'm currently cd into. I
>> use this all the time to track, e.g., what histogram I want to fit at
>> a given time.
>>
>> But TF1's don't behave the same way even though they all inherit from
>> TObject and should I think behave the same way.
>>
>> Is this a bug or a feature? Is this a well known problem?
>>
>> I can certainly kuldge my way around it -- by assign some differing
>> names that I'll have to keep track of, but it does add another layer
>> of possibley buggy bookkeeping that I thought root was doing for me.
>>
>> -Art S
>>
>> Example:
>>
>> A as parameter 1 = 0.0171368; B has par1=0.0205642
>>
>> root [0] A=new TFile("Res_funsT.root")
>> (class TFile*)0x8db4540
>> root [1] .ls
>> TFile** Res_funsT.root
>> TFile* Res_funsT.root
>> KEY: TF1 sigmaPar;1 pol4
>> KEY: TF1 apar;1 pol0
>> KEY: TF1 npar;1 pol0
>> KEY: TF1 mupar;1 pol3
>> KEY: TF1 power;1
>> [0]*([3]*TMath::Gaus(x,[1],[2],1)+(1.0-[3])*TMath::Gaus(x,[4],[5],1))
>> KEY: TF1 pnorm;1 [0]*(1-TMath::Exp(-[1]*x))*(1-TMath::Exp(-[1]*x))
>> root [2] sigmaPar->Print()
>> sigmaPar : pol4 Ndim= 1, Npar= 5, Noper= 1
>> fExpr[0] = pol4 action = 130 action param = 401
>> Optimized expression
>> fExpr[0] = pol4 action = 130 action param = 401
>> Par 0 #alpha_{0} = 0.00493591
>> Par 1 #alpha_{1} = 0.0171368
>> Par 2 #alpha_{2} = -0.00493408
>> Par 3 #alpha_{3} = 0.00143038
>> Par 4 #alpha_{4} = -0.000135192
>> root [3] B=new TFile("testTF1.root")
>> (class TFile*)0x8df5f58
>> root [4] B->cd()
>> (Bool_t)1
>> root [5] sigmaPar->Print()
>> sigmaPar : pol4 Ndim= 1, Npar= 5, Noper= 1
>> fExpr[0] = pol4 action = 130 action param = 401
>> Optimized expression
>> fExpr[0] = pol4 action = 130 action param = 401
>> Par 0 #alpha_{0} = 0.00493591
>> Par 1 #alpha_{1} = 0.0171368
>> Par 2 #alpha_{2} = -0.00493408
>> Par 3 #alpha_{3} = 0.00143038
>> Par 4 #alpha_{4} = -0.000135192
>>
>> --actually it seems to be more a question of which version of
>> function I look at 1st; if open A, don't look at it, then open B,
>> I'll get B values, but A->cd() will not get me the A values.
>>
>>
>>
>> A.E. Snyder, Group EC \!c*p?/
>> SLAC Mail Stop #95 ((. .))
>> Box 4349 |
>> Stanford, Ca, USA, 94309 '\|/`
>> e-mail:snyder_at_slac.stanford.edu o
>> phone:650-926-2701 _
>> http://www.slac.stanford.edu/~snyder BaBar
>> FAX:650-926-2657 Collaboration
>>
>>
>>
>> On Wed, 4 Apr 2007, Philippe Canal wrote:
>>
>>> Hi Arthur,
>>>
>>> I can not reproduce the problem (or do not understand your
>>> description :) ).
>>>
>>> Can you send me a complete running example (and the output as you
>>> see it)
>>> as well as the version of ROOT where it fails for you).
>>>
>>> Cheers,
>>> Philippe.
>>>
>>> -----Original Message-----
>>> From: owner-roottalk_at_pcroot.cern.ch
>>> [mailto:owner-roottalk_at_pcroot.cern.ch]
>>> On Behalf Of Arthur E. Snyder
>>> Sent: Monday, April 02, 2007 4:43 PM
>>> To: Rene Brun
>>> Cc: 'roottalk (Mailing list discussing all aspects of the ROOT system)'
>>> Subject: [ROOT] TString bug (or feature)?
>>>
>>> Hi Rene et al.,
>>>
>>> I find that when I try to read the blank separated charachters in a
>>> line
>>> into TString from an istringstream it has a strange behavior. If the
>>> last
>>> character is followed directly by a line-feed it gets skipped.
>>> Apparently
>>> eof or something is set by reading it and the loop ends w.o. giving
>>> you a
>>> chance at the characters just read. The result is you lose the last
>>> character string. If I use std::string instead, it works as I expect it
>>> too.
>>>
>>> The code is as follows:
>>>
>>> #include "readCard.hh"
>>> #include <TString.h>
>>> #include <iostream>
>>> #include <vector>
>>> #include <string>
>>>
>>> using std::istream;
>>> using std::endl;
>>> using std::cout;
>>>
>>> //read strings till "eol" marker or natural end; if nread!=0 read nread
>>> string (no marker)
>>> Int_t readCard(istream& card,std::vector<TString>& list,Int_t nread) {
>>> Int_t count=0;
>>>
>>> TString temp;
>>> // std::string temp;
>>> while(card >> temp) {
>>>
>>> cout << "count:" << count << " temp:" << temp << endl;
>>>
>>> if(nread==0 && temp=="eol") break;
>>> if(nread==0 && temp=="*eol") break;
>>> if(nread==0 && temp=="!eol") break;
>>> count++;
>>>
>>> list.push_back(temp);
>>> if(count==nread) break;
>>>
>>> } // loop
>>>
>>> return count;
>>> }
>>>
>>> -Art S.
>>>
>>>
>>>
>>
>
Received on Thu Jan 29 2009 - 00:04:46 CET

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