Re: [ROOT] contour plot (fwd)

From: Giacomo Bruno (Giacomo.Bruno@cern.ch)
Date: Tue Aug 06 2002 - 15:27:46 MEST


On Mon, 5 Aug 2002, Rene Brun wrote:

> Could you send me evidence that the option (cont List) returning
> a list of TGraphs does not work (C++ macro and a Root file)?


Hi Rene,
sorry for the late answer, but my delay was due to some changement of
behaviour I have observed as I was preparing the macro and the root file
for you to check.

You can find the macro and the root file under

/afs/cern.ch/user/g/gbruno/public/For_Rene/

Part of the problems (unpredictable behaviour) have disappeared as soon as
I got rid of a library that I used to load at the beginning of the macro,
but that I was not  actually  using to make that particular contour plot.
This library had
been compiled separately with the compiler used by the reconstruction
program ORCA of CMS (gcc 2.95.2). I have not understood yet why this
caused problems but I guess it could be linked to some conflict
since in the library I was using the class TObjArray.

However after removing the load of this library I have still error
messages.
Actually I have now realized (after restarting root from
scratch), that the error occurs at different lines according to the past
of the root session.

The last error I get is

Error: illegal pointer to class object contours 0x0 219  FILE:Rene.C
LINE:95

Before restarting root, this line was not giving any problem. Instead I
could not get access to contour 9 , the last of the 10 I set. The other
contours seemed to be ok.
The error was

Error: illegal pointer to class object contours 0x0 219  FILE:Rene.C
LINE:101
*** Interpreter error recovered ***


I hope you will be able to help me

cheers
Giacomo




>
> Rene Brun
>
> On Mon, 5 Aug 2002, Giacomo Bruno wrote:
>
> >
> > Hi
> >  I would like to draw a 2-d histogram in contour format showing the levels
> >  with lines of different colours. I get the lines as expected, but then I
> > would also like to draw a legend.
> > To this aim I need to retrieve in some way the colours id
> > of the lines. On the user's guide 3.02 at page 42 it is explained how to
> > access the TGraph objects that are created when drawing a contour plot, however when I
> > tried it everything happened (sometimes crashes, sometimes wrong results and
> > almost always running the same code gave different results). I was then obliged to
> > guess the colours and set them by hand. Does anyone have an idea on how to
> > solve this problem?
> >  Thanks in advance
> >
> > cheers
> >  Giacomo
> >
> >
> >
> >   -----------------------------------------
> >  |            Giacomo BRUNO                |
> >  |                                         |
> >  |            CERN			   |
> >  |	      EP Division		   |
> >  |					   |
> >  | mail:      40-2-B20                     |
> >  |            C.E.R.N.                     |
> >  |            CH - 1211 Geneva 23          |
> >  |            Switzerland                  |
> >  | e-mail:    Giacomo.Bruno@cern.ch        |
> >  | phone:     +41 22 76 71624		   |
> >   -----------------------------------------
> >
> >
> >
>
>

  -----------------------------------------
 |            Giacomo BRUNO                |
 |                                         |
 |            CERN			   |
 |	      EP Division		   |
 |					   |
 | mail:      40-2-B20                     |
 |            C.E.R.N.                     |
 |            CH - 1211 Geneva 23          |
 |            Switzerland                  |
 | e-mail:    Giacomo.Bruno@cern.ch        |
 | phone:     +41 22 76 71624		   |
  -----------------------------------------



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