White overlay with TMultiGraph

ROOT
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1

ROOT Version: 6.28/04
Platform: WSL 1, Ubuntu 20.04
Compiler: gcc 9.4.0

Hi,

I am facing problems with visualizing ~40 TGraphs on the same canvas. The following script
superimpose_EOS_massive.py (1.6 KB)
reads same structure TGraph from multiple rootfiles, which I intended to superimpose. Sample rootfile follows
cooling_curve_mass_1.48.root (63.0 KB).
To a sad surprise, the result looks very eye-cutting
cooling_curves_many.pdf (318.1 KB)
, which appears to me that multiple graph overlays are replaced with white. I could not find a good workaround, which included messing with linestyles, linesizes, canvas sizes etc. It is, of course, essential to receive pdf as the end product.

Could you please suggest?
Thank you.

2

Don’t do cooling_curve.SetLineColor(i) if i goes from 0 to a high value. See the corresponding colours here:
https://root.cern/doc/master/classTColor.html#C01
Some alternatives:

  • define an array with the numbers of the colours you want to use from the basic colours above
  • define an array with the colours from the “color wheel” (same page as above), for more options
  • create your own table of colours with CreateGradientColorTable and use these; you can read about it on the same TColor page, and here:
    ROOT: tutorials/graphs/multipalette.C File Reference
    Note in particular these lines
      Int_t FI = TColor::CreateGradientColorTable(3,Length,Red,Green,Blue,50);
      for (int i=0; i<50; i++) colors[i] = FI+i;

For pyroot, see for example

3

Thank you for your commentary, that is some useful stuff on TColor. I did not expect many colours to be used (as mentioned, only 40 TGraphs), yet you pointed me on the clue. I iterated over the same TGraphs for 1400 times by accident, that is why I ran so well out of palette.

Appreciate your help!
Pavlo