rf509_wsinteractive.py

Go to the documentation of this file.

## \file
## \ingroup tutorial_roofit
## \notebook
## Organization and simultaneous fits: easy interactive access to workspace contents - CINT
## to CLING code migration
##
## \macro_image
## \macro_code
## \macro_output
##
## \date February 2018
## \authors Clemens Lange, Wouter Verkerke (C++ version)
 
import ROOT
 
 
def fillWorkspace(w):
    # Create pdf and fill workspace
    # --------------------------------------------------------
 
    # Declare observable x
    x = ROOT.RooRealVar("x", "x", 0, 10)
 
    # Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and
    # their parameters
    mean = ROOT.RooRealVar("mean", "mean of gaussians", 5, 0, 10)
    sigma1 = ROOT.RooRealVar("sigma1", "width of gaussians", 0.5)
    sigma2 = ROOT.RooRealVar("sigma2", "width of gaussians", 1)
 
    sig1 = ROOT.RooGaussian("sig1", "Signal component 1", x, mean, sigma1)
    sig2 = ROOT.RooGaussian("sig2", "Signal component 2", x, mean, sigma2)
 
    # Build Chebychev polynomial pdf
    a0 = ROOT.RooRealVar("a0", "a0", 0.5, 0.0, 1.0)
    a1 = ROOT.RooRealVar("a1", "a1", -0.2, 0.0, 1.0)
    bkg = ROOT.RooChebychev("bkg", "Background", x, [a0, a1])
 
    # Sum the signal components into a composite signal pdf
    sig1frac = ROOT.RooRealVar("sig1frac", "fraction of component 1 in signal", 0.8, 0.0, 1.0)
    sig = ROOT.RooAddPdf("sig", "Signal", [sig1, sig2], [sig1frac])
 
    # Sum the composite signal and background
    bkgfrac = ROOT.RooRealVar("bkgfrac", "fraction of background", 0.5, 0.0, 1.0)
    model = ROOT.RooAddPdf("model", "g1+g2+a", [bkg, sig], [bkgfrac])
 
    w.Import(model)
 
 
# Create and fill workspace
# ------------------------------------------------
 
 
# Create a workspace named 'w'
# With CINT w could exports its contents to
# a same-name C++ namespace in CINT 'namespace w'.
# but self does not work anymore in CLING.
# so self tutorial is an example on how to
# change the code
w = ROOT.RooWorkspace("w", True)
 
# Fill workspace with pdf and data in a separate function
fillWorkspace(w)
 
# Print workspace contents
w.Print()
 
# self does not work anymore with CLING
# use normal workspace functionality
 
# Use workspace contents
# ----------------------------------------------
 
# Old syntax to use the name space prefix operator to access the workspace contents
#
# d = w.model.generate(w.x,1000)
# r = w.model.fitTo(*d)
 
# use normal workspace methods
model = w["model"]
x = w["x"]
 
d = model.generate({x}, 1000)
r = model.fitTo(d, PrintLevel=-1)
 
# old syntax to access the variable x
# frame = w.x.frame()
 
frame = x.frame()
d.plotOn(frame)
 
# OLD syntax to omit x.
# NB: The 'w.' prefix can be omitted if namespace w is imported in local namespace
# in the usual C++ way
#
# using namespace w
# model.plotOn(frame)
# model.plotOn(frame, Components=bkg, LineStyle="--")
 
# correct syntax
bkg = w["bkg"]
model.plotOn(frame)
model.plotOn(frame, Components=bkg, LineStyle="--")
 
# Draw the frame on the canvas
c = ROOT.TCanvas("rf509_wsinteractive", "rf509_wsinteractive", 600, 600)
ROOT.gPad.SetLeftMargin(0.15)
frame.GetYaxis().SetTitleOffset(1.4)
frame.Draw()
 
c.SaveAs("rf509_wsinteractive.png")