import ROOT

ROOT.gROOT.SetStyle("Plain")

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

mu1 = ROOT.RooRealVar("mu1", "average 1", 0, -1, 1)
sigma1 = ROOT.RooRealVar ("sigma1", "sigma 1", 1, 0, 5)
gauss1 = ROOT.RooGaussian("gauss1","gaussian 1 PDF", x, mu1, sigma1)

mu2 = ROOT.RooRealVar("mu2", "average 2", 0.5, -1, 1)
sigma2 = ROOT.RooRealVar("sigma2", "sigma 2", 0.5, 0, 5)
gauss2 = ROOT.RooGaussian("gauss2","gaussian 2 PDF", x, mu2, sigma2)

mu3 = ROOT.RooRealVar("mu3", "average 2", -0.5, -1, 1)
sigma3 = ROOT.RooRealVar("sigma3", "sigma 2", 1.5, 0, 5)
gauss3 = ROOT.RooGaussian("gauss3","gaussian 2 PDF", x, mu3, sigma3)

xFrame = x.frame()
gauss1.plotOn(xFrame, ROOT.RooFit.LineColor(ROOT.kRed))
gauss2.plotOn(xFrame, ROOT.RooFit.LineColor(ROOT.kBlue))
gauss3.plotOn(xFrame, ROOT.RooFit.LineColor(ROOT.kMagenta))
c = ROOT.TCanvas()
xFrame.Draw()
c.SaveAs("01-gaussians.pdf")