chi2FitTo methods not exposed to pyroot

Roofit and RooStats
1

Using ROOT 6.18.04, it seems as though all the implemented methods for chi2FitTo are not exposed to all PDFs, but rather only the one used in the tutorial rf609_xychi2fit.

Python 3.7.4 (default, Sep  7 2019, 18:27:02) 
[Clang 10.0.1 (clang-1001.0.46.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ROOT as R
>>> R.RooPolyVar.chi2FitTo()

RooFit v3.60 -- Developed by Wouter Verkerke and David Kirkby 
                Copyright (C) 2000-2013 NIKHEF, University of California & Stanford University
                All rights reserved, please read http://roofit.sourceforge.net/license.txt

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: none of the 4 overloaded methods succeeded. Full details:
  RooFitResult* RooAbsReal::chi2FitTo(RooDataHist& data, const RooCmdArg& arg1 = RooCmdArg::none(), const RooCmdArg& arg2 = RooCmdArg::none(), const RooCmdArg& arg3 = RooCmdArg::none(), const RooCmdArg& arg4 = RooCmdArg::none(), const RooCmdArg& arg5 = RooCmdArg::none(), const RooCmdArg& arg6 = RooCmdArg::none(), const RooCmdArg& arg7 = RooCmdArg::none(), const RooCmdArg& arg8 = RooCmdArg::none()) =>
    unbound method RooAbsReal::chi2FitTo must be called with a RooAbsReal instance as first argument
  RooFitResult* RooAbsReal::chi2FitTo(RooDataHist& data, const RooLinkedList& cmdList) =>
    unbound method RooAbsReal::chi2FitTo must be called with a RooAbsReal instance as first argument
  RooFitResult* RooAbsReal::chi2FitTo(RooDataSet& xydata, const RooCmdArg& arg1 = RooCmdArg::none(), const RooCmdArg& arg2 = RooCmdArg::none(), const RooCmdArg& arg3 = RooCmdArg::none(), const RooCmdArg& arg4 = RooCmdArg::none(), const RooCmdArg& arg5 = RooCmdArg::none(), const RooCmdArg& arg6 = RooCmdArg::none(), const RooCmdArg& arg7 = RooCmdArg::none(), const RooCmdArg& arg8 = RooCmdArg::none()) =>
    unbound method RooAbsReal::chi2FitTo must be called with a RooAbsReal instance as first argument
  RooFitResult* RooAbsReal::chi2FitTo(RooDataSet& xydata, const RooLinkedList& cmdList) =>
    unbound method RooAbsReal::chi2FitTo must be called with a RooAbsReal instance as first argument
>>> R.RooGaussian.chi2FitTo()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: RooFitResult* RooAbsPdf::chi2FitTo(RooDataHist& data, const RooLinkedList& cmdList) =>
    unbound method RooAbsPdf::chi2FitTo must be called with a RooAbsPdf instance as first argument
>>> R.RooGenericPdf.chi2FitTo()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: RooFitResult* RooAbsPdf::chi2FitTo(RooDataHist& data, const RooLinkedList& cmdList) =>
    unbound method RooAbsPdf::chi2FitTo must be called with a RooAbsPdf instance as first argument
>>>

Is there a way to make these exposed in user code?

2

Hi @adam.davis,

thanks for reporting that. Can you reach the different overloads if you actually pass the mandatory first argument? Without arguments, none of the function calls can work.

I agree that the reporting might be broken, but we are working on a new PyROOT where this hopefully will work in a more consistent way.

3

I actually tried reaching the different overloads first with a full blown analysis, but actually couldn’t reach them at all, so tried to get the minimal working example. Here’s a reproduction:

Python 3.7.4 (default, Sep  7 2019, 18:27:02) 
[Clang 10.0.1 (clang-1001.0.46.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ROOT as R
>>> mu = R.RooRealVar("mu","mu",-1.0,1.0)

RooFit v3.60 -- Developed by Wouter Verkerke and David Kirkby 
                Copyright (C) 2000-2013 NIKHEF, University of California & Stanford University
                All rights reserved, please read http://roofit.sourceforge.net/license.txt

>>> sig = R.RooRealVar("sig","sig",0.1,1.0)
>>> x = R.RooRealVar(
... "x","x",-5,5)
>>> g = R.RooGaussian("g","g",x,mu,sig)
>>> ds = R.RooDataSet("ds","ds",R.RooArgSet(x,mu,sig))
>>> g.chi2FitTo(ds)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: RooFitResult* RooAbsPdf::chi2FitTo(RooDataHist& data, const RooLinkedList& cmdList) =>
    takes at least 2 arguments (1 given)
>>>
4

Ok, that’s indeed a shortcoming of PyROOT. It doesn’t understand if a function overload comes into a derived class with using.
I can write an explicit python function for that. I will track the progress here:
https://sft.its.cern.ch/jira/browse/ROOT-10503

Update

Tomorrow (Tue 14th), they should work in ROOT’s nightly:
https://root.cern/nightlies

Workaround for old ROOT versions

As a temporary workaround, call it with an empty RooLinkedList as second argument as suggested in the first mention of this problem:
https://sft.its.cern.ch/jira/browse/ROOT-7938

arglist = R.RooLinkedList()
testfunc.chi2FitTo(testdata, arglist)

Note that if you want to put items into the list, you need to keep a python object alive:

arglist = R.RooLinkedList()
saveArg = R.RooFit.Save()
arglist.add(saveArg)
testfunc.chi2FitTo(testdata, arglist)

If you don’t keep saveArg, python will just delete it because it doesn’t know that this object is also being used in C++.

5

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.