PyROOT issues with TH2D::FitSlicesX and ROOSTATS::LikelihoodIntervalPlot::Draw()

ROOT
#1

Dear all,

I encountered a rather peculiar behaviour in a Python I am currently writing and in which I use PyROOT. I first fit a TH2D using FitSlicesX. Later in my program I use Roostats to compute and draw a LikelihoodIntervalPlot. These two actions are executed within a for loop running of several files. At the first iteration everything is fine. However, at the second iteration the code crashes with the following Traceback Error :

***** Break *** segmentation violation**
---------------------------------------------------------------------------
SystemError Traceback (most recent call last)
/Users/mougeot_maxime/ownCloud/Documents/Argon/analysis/test_profile_draw.py in ()
34 tobj = ROOT.TObjArray()
35 f1 = ROOT.TF1(‘f1’,‘gaus(0)’,roilow,roimax)
—> 36 th2.FitSlicesX(f1,0,-1,0,‘QNR’,tobj)
37 data = ROOT.RooDataHist(“data”,“data”,
38 ROOT.RooArgList(t),\

SystemError: problem in C++; program state has been reset

I tracked the problem down as being due to the call of the Draw() function on my LikelihoodIntervalPlot object. When I comment out the call to draw the code terminates fine . My original code is rather long but I put together a small code which seems to show the same behaviour. I put the latter in attachment.

I would greatly appreciate some insights from more experienced people concerning this issue.

Thank you all in advance.

test_profile_draw.py (2.3 KB)
test_data.txt (69.9 KB)

#2

I suspect a mismatch in Python vs C++ - but I’ve asked @etejedor and @mato for help; maybe they have an idea? If I were you I’d call f1.Dump() and th2.Dump() before the failing line, to make sure they are what you expect them to be.

#3

It does not seem a PyROOT issue, the attached C++ reproducer also segfaults with the same error. Looks like a double delete inside the TMinuitMinimizer destructor. Attaching also the error thrown by @smaxwell’s code and by the C++ reproducer.

test.C (1.8 KB)

python_err.txt (34.4 KB)

cpp_err.txt (20.3 KB)

#4

Thanks for taking the time to investigate this issue.

Does it mean it is a ROOT issue or is there just something fishy in the way I built the code ?

I could try to compute the profile likelihood using RooFit instead of RooStats and see what happens.

Regards,

MM

#5

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