Extracting fitted bin counts from RooFit PDF

Motivation

Having performed a fit with RooFit, it is often required to extract the fitted event count in each bin. This is possible, as shown in the example below. The input variables are:

fitMin The lower edge of the fitted region
fitMax The upper edge of the fitted region
observable The observable parameter of the fit (i.e. x-axis of 1D PDF)
fittedPdf A fitted PDF
lowBinEdge The lower edge of the bin of interest
highBinEdge The upper edge of the bin of interest
numEventsInFitRange The number of events in the fitted data between fitMin and fitMax

Code example

observable->setRange("bin", fitMin, fitMax);
RooAbsReal* intPdf = fittedPdf->createIntegral(*observable, Range("bin"));
double scaling = numEventsInFitRange / intPdf->getVal();
observable->setRange("bin", lowBinEdge, highBinEdge);
double binCount = intPdf->getVal() * scaling;
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Topic revision: r2 - 2009-05-26 - JamesJackson
 
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