Color Axis Label Size


I am plotting a 2D histo w/ colz option. The labels on the color axis however are too big. I can easily change their size in the interactive pad way, but would like to have my program do this automatically. All that i really need to do is to get the TPaletteAxis from the canvas which is automatically names “palette”. However i tried :

TPaletteAxis *pal = gPad->FindObject(“palette”);

which runs error free but gives an empty pointer of that class, to which i cannot perform the necessary action.

There must be an obvious way that i can get this palette in order to modify it that i am missing somewhere.

If any one could help me, i would really appreciate it.

Thanks in advance,

Mitch C.

The palette is connected to the histogram list of functions. See class description of TPaletteAxis at:

To change the label size, do:
TPaletteAxis *pal = h->GetListOfFunctions()->FindObject(“palette”);


thanks a lot

mitch c.

Actually, i had though that this worked, because i tested it in root and performed what i wanted.

However, I had forgotten (and forgotten to mention) , that i have to run root in batch mode. This way doesnt seem to work for root in batch mode.

root -b

root: TH2F *h = new TH2F("","",10,0,10,10,0,10);
root: h->Fill(3,3);
root: h->Draw(“colz”);
root: TPaletteAxis pal = (TPaletteAxis) (h->GetListOfFunctions()->FindObject(“palette”));
root: pal->GetAxis()->SetLabelSize(.3);
Error: illegal pointer to class object pal 0x0 972 FILE:(tmpfile) LINE:1
*** Interpreter error recovered ***

it seems that the palette gets returned as a blank pointer of type TPaletteAxis. I guess that the color axis palette is not accesible in the same when when running in batch mode.

Sorry for wasting your time with the first question, i obviously didn’t know what i was talking about.

Is there a way to do this?
If anyone could help it would be really appreciated.

Thanks ,

Mitch C.

I suggest you read the chapter about Graphics in the Users Guide or at least
The objects such as the TPaveStats box or the TPaletteAxis are created only when effectively painting the histogram. Simply calling Draw adds a reference to the list of primitives in the pad.
Before accessing your TPaletteAxis object, you should call
In an interactive session, this is automatic when you press CR