doc/v628/rf301__composition_8py.html

import ROOT


# Setup composed model gauss(x, m(y), s)

# -----------------------------------------------------------------------


# Create observables

x = ROOT.RooRealVar("x", "x", -5, 5)

y = ROOT.RooRealVar("y", "y", -5, 5)


# Create function f(y) = a0 + a1*y

a0 = ROOT.RooRealVar("a0", "a0", -0.5, -5, 5)

a1 = ROOT.RooRealVar("a1", "a1", -0.5, -1, 1)

fy = ROOT.RooPolyVar("fy", "fy", y, [a0, a1])


# Creat gauss(x,f(y),s)

sigma = ROOT.RooRealVar("sigma", "width of gaussian", 0.5)

model = ROOT.RooGaussian("model", "Gaussian with shifting mean", x, fy, sigma)


# Sample data, plot data and pdf on x and y

# ---------------------------------------------------------------------------------


# Generate 10000 events in x and y from model

data = model.generate({x, y}, 10000)


# Plot x distribution of data and projection of model x = Int(dy)

# model(x,y)

xframe = x.frame()

data.plotOn(xframe)

model.plotOn(xframe)


# Plot x distribution of data and projection of model y = Int(dx)

# model(x,y)

yframe = y.frame()

data.plotOn(yframe)

model.plotOn(yframe)


# Make two-dimensional plot in x vs y

hh_model = model.createHistogram("hh_model", x, Binning=50, YVar=dict(var=y, Binning=50))

hh_model.SetLineColor(ROOT.kBlue)


# Make canvas and draw ROOT.RooPlots

c = ROOT.TCanvas("rf301_composition", "rf301_composition", 1200, 400)

c.Divide(3)

c.cd(1)

ROOT.gPad.SetLeftMargin(0.15)

xframe.GetYaxis().SetTitleOffset(1.4)

xframe.Draw()

c.cd(2)

ROOT.gPad.SetLeftMargin(0.15)

yframe.GetYaxis().SetTitleOffset(1.4)

yframe.Draw()

c.cd(3)

ROOT.gPad.SetLeftMargin(0.20)

hh_model.GetZaxis().SetTitleOffset(2.5)

hh_model.Draw("surf")


c.SaveAs("rf301_composition.png")