doc/v618/rf203__ranges_8py.html

from __future__ import print_function

import ROOT


# Set up model

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


# Construct observables x

x = ROOT.RooRealVar("x", "x", -10, 10)


# Construct gaussx(x,mx,1)

mx = ROOT.RooRealVar("mx", "mx", 0, -10, 10)

gx = ROOT.RooGaussian("gx", "gx", x, mx, ROOT.RooFit.RooConst(1))


# px = 1 (flat in x)

px = ROOT.RooPolynomial("px", "px", x)


# model = f*gx + (1-f)px

f = ROOT.RooRealVar("f", "f", 0., 1.)

model = ROOT.RooAddPdf(

    "model", "model", ROOT.RooArgList(gx, px), ROOT.RooArgList(f))


# Generated 10000 events in (x,y) from p.d.f. model

modelData = model.generate(ROOT.RooArgSet(x), 10000)


# Fit full range

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


# Fit p.d.f to all data

r_full = model.fitTo(modelData, ROOT.RooFit.Save(ROOT.kTRUE))


# Fit partial range

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


# Define "signal" range in x as [-3,3]

x.setRange("signal", -3, 3)


# Fit p.d.f only to data in "signal" range

r_sig = model.fitTo(modelData, ROOT.RooFit.Save(

    ROOT.kTRUE), ROOT.RooFit.Range("signal"))


# Plot/print results

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


# Make plot frame in x and add data and fitted model

frame = x.frame(ROOT.RooFit.Title("Fitting a sub range"))

modelData.plotOn(frame)

model.plotOn(

    frame, ROOT.RooFit.Range("Full"), ROOT.RooFit.LineStyle(

        ROOT.kDashed), ROOT.RooFit.LineColor(

            ROOT.kRed)) # Add shape in full ranged dashed

model.plotOn(frame)  # By default only fitted range is shown


# Print fit results

print("result of fit on all data ")

r_full.Print()

print("result of fit in in signal region (note increased error on signal fraction)")

r_sig.Print()


# Draw frame on canvas

c = ROOT.TCanvas("rf203_ranges", "rf203_ranges", 600, 600)

ROOT.gPad.SetLeftMargin(0.15)

frame.GetYaxis().SetTitleOffset(1.4)

frame.Draw()


c.SaveAs("rf203_ranges.png")