Bug or feature?

From: Arthur E. Snyder <snyder_at_slac.stanford.edu>
Date: Wed, 28 Jan 2009 14:35:12 -0800

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 Wed Jan 28 2009 - 23:35:21 CET