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Some bugs in TMVA MultiClassGui

Dear experts,

I am writing to report some bugs that I have noticed in TMVAMultiClassGui

The relevant ROOT Version is 6.22.02. I am invoking it on lxplus using

source /cvmfs/sft.cern.ch/lcg/app/releases/ROOT/6.22.02/x86_64-centos7-gcc48-opt/bin/thisroot.sh

I am placing the output ROOT file from training in my public directory on lxplus at


Upon doing

root -l
root [0] TMVA::TMVAMultiClassGui("TMVA_Comb_noCV_split.root")

I notice the folowing:

  1. Buttons 4b - Drawing of Classifier Output Distributions for Training and Testing samples superimposed : I am unable to interactively right click on the components drawn on the canvases and change attributes like line color, fill color etc, AFTER zooming in on a canvas. The individual TH1F objects are just not selectable. Even before zooming in, only the training histograms appear to be selectable, not the testing ones.
    I can also see this effect in view->Event Statusbar. When I hover my mouse over the objects after zooming, their names don’t show up on the status bar. Instead, I just see the name of the canvas.

  2. Button 4a - Drawing of Classifier Output Distributions for Testing sample alone - None of the objects drawn on the canvas are selectable, even before zooming in. Only the frame itself gets selected every time I right click.

  3. Buttons 5 and 6 - ROC Curves - For one vs rest (Button 5), only one of the canvases drawn actually has a ROC curve. The rest are empty. For one vs one, again only a few canvases have ROC curves. The rest are empty.

I wished to bring these to your attention. I would be happy to provide any more info that is needed from my side.


Hello @avenkate,

thanks for getting in touch. I invite @moneta to have a look.

Hi @moneta,

Have you had a chance to take a look at this?



yes, I could reproduce the problem. I’ll try in the next days to understand the cause and fix


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Hi @moneta ,

I am pinging to keep this thread from closing.


Sorry for the late reply.
A PR is now open fixing this: https://github.com/root-project/root/pull/6462


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