[RF] Completely implement Offset("bin") feature

[guitargeek]

Fully implement and test the new Offset("bin") feature over the test matrix that is the tensor product of BatchMode(), doing and extended fit, RooDataSet vs. RooDataHist, and SumW2 correction. The test should compute the likelihood for a template PDF created from the data, and it should be numerically compatible with zero.

void testOffsetBin()
{
   using namespace RooFit;
   using RealPtr = std::unique_ptr<RooAbsReal>;

   // Create extended PDF model
   RooRealVar x("x", "x", -10, 10);
   RooRealVar mean("mean", "mean", 0, -10, 10);
   RooRealVar sigma("sigma", "width", 4, 0.1, 10);
   RooRealVar nEvents{"n_events", "n_events", 10000, 100, 100000};

   RooGaussian gauss("gauss", "gauss", x, mean, sigma);
   RooAddPdf extGauss("extGauss", "extGauss", gauss, nEvents);

   std::unique_ptr<RooDataSet> data{extGauss.generate(x)};

   {
      // Create weighted dataset and hist to test SumW2 feature
      RooRealVar weight("weight", "weight", 0.5, 0.0, 1.0);
      auto dataW = std::make_unique<RooDataSet>("dataW", "dataW", RooArgSet{x, weight}, "weight");
      for (std::size_t i = 0; i < data->numEntries(); ++i) {
         dataW->add(*data->get(i), 0.5); // try weights that are different from unity
      }
      std::swap(dataW, data); // try to replace the original dataset with weighted dataset
   }

   std::unique_ptr<RooDataHist> hist{data->binnedClone()};

   data->Print();
   hist->Print();

   // Create template PDF based on data
   RooHistPdf histPdf{"histPdf", "histPdf", x, *hist};
   RooAddPdf extHistPdf("extHistPdf", "extHistPdf", histPdf, nEvents);

   auto& pdf = extHistPdf;

   auto const bm = "off"; // it should also work work BatchMode("cpu")

   double nllVal01 = RealPtr{pdf.createNLL(*data, BatchMode(bm), Extended(false))}->getVal();
   double nllVal02 = RealPtr{pdf.createNLL(*data, BatchMode(bm), Extended(true)) }->getVal();
   double nllVal03 = RealPtr{pdf.createNLL(*hist, BatchMode(bm), Extended(false))}->getVal();
   double nllVal04 = RealPtr{pdf.createNLL(*hist, BatchMode(bm), Extended(true)) }->getVal();

   double nllVal1  = RealPtr{pdf.createNLL(*data, BatchMode(bm), Offset("bin"), Extended(false))}->getVal();
   double nllVal2  = RealPtr{pdf.createNLL(*data, BatchMode(bm), Offset("bin"), Extended(true)) }->getVal();
   double nllVal3  = RealPtr{pdf.createNLL(*hist, BatchMode(bm), Offset("bin"), Extended(false))}->getVal();
   double nllVal4  = RealPtr{pdf.createNLL(*hist, BatchMode(bm), Offset("bin"), Extended(true)) }->getVal();

   // The final unit test should also include the SumW2 option in the test matrix

   // For all configurations, the bin offset should have the effect of bringing
   // the NLL close to zero:
   std::cout << "Unbinned fit      :  " << nllVal01 << "    " << nllVal1 << std::endl;
   std::cout << "Unbinned ext. fit : " << nllVal02 << "   " << nllVal2 << std::endl;
   std::cout << "Binned fit        :  " << nllVal03 << "   " << nllVal3 << std::endl;
   std::cout << "Binned ext. fit   : " << nllVal04 << "   " << nllVal4 << std::endl;
}

[guitargeek]

Re-opening because I still need to implement this feature for fits with a RooDataSet

[dgwnb]

Hi all,

This is Hongtao from ATLAS Higgs working group. I am the maintainer of xml analytic workspace builder and quickFit. Thank you very much for implementing this very important feature. As yo probably know, however, when making workspaces we usually use weighted RooDataSet instead of RooDataHist to store binned data. Therefore if you could make this feature available for binned RooDataSet it would be very handy for us to further test this feature in physics analyses. Thank you.

[JackHLindon]

Hi, I would also like to give my support for this being available for RooDataSet

[Falk-Bartels]

Thanks @guitargeek for the great addition of the Offset("bin") option. Very interested to see it supported for RooDataSet as well to use it in quickFit.

[github-actions]

Hi @guitargeek,

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,
🤖