TScatter palette settings

[ferdymercury]

Explain what you would like to see improved and how.

In the new TScatter class, it was found here https://root-forum.cern.ch/t/scatter-plot-with-colorbar/59562/14 that:

• There is not an easy way to control the color bar range
• Save TScatter object as .C and reload it, then the palette axis title is lost. The function SavePrimitive should be amended.

ROOT version

ROOT v6.32.00
Built for linuxx8664gcc on May 28 2024, 05:02:02
From tags/v6-32-00@v6-32-00
With c++ (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
Binary directory: /opt/root/bin

Installation method

Binary Release

Operating system

Ubuntu 22.04

Additional context

No response

[github-actions]

Hi @couet,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

[ferdymercury]

Thanks for the fix @couet!

I would also suggest adding an alternative way (commented) in the tutorial to "zoom" rather than "setting user range", namely to use:

   scatter->GetHistogram()->SetMinimum(10);
   scatter->GetHistogram()->SetMaximum(200);

This way, the palette is also zoomed, unlike with SetUserRange, which just acts as a filter on what points to plot or not.

Also: there is a bug:

• If one calls SetMinimum only, then the plot is broken. If that's intended, then maybe we should create a function scatter->SetMinMax() so that people don't forget to put both.

• the behavior of the TH2F when zooming Z-axis is different from TScatter. In TH2F, colors outside the range are clipped to max or min color. Here in TScatter, instead of clipping, they are filtered out of the plot. I don't know if that's a good solution, but if it is intended, it should be documented in the Doxygen docu. If not inteded, then the color should be clipped to the max/min of the palette.