"Underflow" color in TH2-COLZ

moritz · June 1, 2006, 8:38pm

Hi ROOTers,

I have to apologize in advance for the (likely) case the answer to this question is trivial or given already. I just didn’t find it.

I am drawing a TH2D with the “COLZ” option and the “fancy” palette (gStyle->SetPalette(1)). The range of the color scale is adjusted with histo->SetMaximum / SetMinimum.

Any bin with contents greater than the scale’s maximum is drawn in red, which means “overflow - out of range”. This is perfect. But bins with contents smaller than the scale’s minimum are set to the frame fill color, as if they were empty. How do I get them drawn in dark blue, meaning “underflow but greater than zero”? Setting gStyle->FrameFillColor to blue is not possible as “nothing at all” and “something but below range” does make a great difference for me. I need a real marker for “just below range”.

Thanks,

Moritz

PPS: Using ROOT 5.08/00.

couet · June 2, 2006, 8:13am

In the code painting the color plot it is explicitly done that way.
It has always been like that. This kind of representation is widely use and any change in the behavior generates many complaints. We cannot change that behavior.
The only solution I can imagine would be to first plot the histogram without range and on top of it the same one with range like with the 2 following commands.

hpxpy->Draw("box");
hpxpy->Draw("colz same");