example.py

Go to the documentation of this file.

## \file
## \ingroup tutorial_histfactory
## A ROOT script demonstrating  an example of writing a HistFactory model using Python.
##
## \macro_code
## \macro_output
##
## \author George Lewis
 
def main():
 
    try:
        import ROOT
    except:
        print("It seems that pyROOT isn't properly configured")
        return
 
    """
    Create a HistFactory measurement from python
    """
 
    InputFile = "./data/example.root"
    if (ROOT.gSystem.AccessPathName(InputFile)) :
        ROOT.Info("example.py", InputFile+" does not exist")
        exit()
 
    # Create the measurement
    meas = ROOT.RooStats.HistFactory.Measurement("meas", "meas")
 
    meas.SetOutputFilePrefix( "./results/example_UsingPy" )
    meas.SetPOI( "SigXsecOverSM" )
    meas.AddConstantParam("Lumi")
    meas.AddConstantParam("alpha_syst1")
 
    meas.SetLumi( 1.0 )
    meas.SetLumiRelErr( 0.10 )
    meas.SetExportOnly( False )
 
    # Create a channel
 
    chan = ROOT.RooStats.HistFactory.Channel( "channel1" )
    chan.SetData( "data", InputFile )
    chan.SetStatErrorConfig( 0.05, "Poisson" )
 
    # Now, create some samples
 
    # Create the signal sample
    signal = ROOT.RooStats.HistFactory.Sample( "signal", "signal", InputFile )
    signal.AddOverallSys( "syst1",  0.95, 1.05 )
    signal.AddNormFactor( "SigXsecOverSM", 1, 0, 3 )
    chan.AddSample( signal )
 
 
    # Background 1
    background1 = ROOT.RooStats.HistFactory.Sample( "background1", "background1", InputFile )
    background1.ActivateStatError( "background1_statUncert", InputFile )
    background1.AddOverallSys( "syst2", 0.95, 1.05  )
    chan.AddSample( background1 )
 
 
    # Background 1
    background2 = ROOT.RooStats.HistFactory.Sample( "background2", "background2", InputFile )
    background2.ActivateStatError()
    background2.AddOverallSys( "syst3", 0.95, 1.05  )
    chan.AddSample( background2 )
 
 
    # Done with this channel
    # Add it to the measurement:
 
    meas.AddChannel( chan )
 
    # Collect the histograms from their files,
    # print some output,
    meas.CollectHistograms()
    meas.PrintTree();
 
    # One can print XML code to an
    # output directory:
    # meas.PrintXML( "xmlFromCCode", meas.GetOutputFilePrefix() );
 
    meas.PrintXML( "xmlFromPy", meas.GetOutputFilePrefix() );
 
    # Now, do the measurement
    ROOT.RooStats.HistFactory.MakeModelAndMeasurementFast( meas );
 
    pass
 
 
if __name__ == "__main__":
    main()