hist034_TRatioPlot_fit_margin.py

## \file
## \ingroup tutorial_hist
## \notebook
## Example showing a fit residual plot, where the separation margin has been set to 0.
## The last label of the lower plot's y axis is hidden automatically.
## Inspired by the tutorial of Paul Gessinger.
##
## \macro_image
## \macro_code
##
## \author Alberto Ferro

import ROOT

ROOT.gStyle.SetOptStat(0)

c1 = ROOT.TCanvas("c1", "fit residual simple")
ROOT.gPad.SetFrameFillStyle(0)

h1 = ROOT.TH1D("h1", "h1", 50, -5, 5)
h1.FillRandom("gaus", 5000)
h1.Fit("gaus", "S")

h1.Sumw2()
h1.GetXaxis().SetTitle("x")
h1.GetYaxis().SetTitle("y")

rp1 = ROOT.TRatioPlot(h1, "errfunc")
rp1.SetGraphDrawOpt("L")
rp1.SetSeparationMargin(0.0)
rp1.Draw()
rp1.GetLowerRefGraph().SetMinimum(-2)
rp1.GetLowerRefGraph().SetMaximum(2)

c1.Update()