hist030_TRatioPlot_residual.py

## \ingroup tutorial_hist

## \notebook

## Example of a fit residual plot.

##

## Creates a histogram filled with random numbers from a gaussian distribution

## and fits it with a standard gaussian function. The result is passed to the `TRatioPlot`

## constructor. Additionally, after calling `TRatioPlot::Draw` the upper and lower y axis

## titles are modified.

## Confidence interval bands are automatically drawn on the bottom (but can be disabled by draw option `nobands`).

## 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")

h1 = ROOT.TH1D("h1", "h1", 50, -5, 5)

h1.FillRandom("gaus", 2000)

h1.Fit("gaus")

h1.GetXaxis().SetTitle("x")

rp1 = ROOT.TRatioPlot(h1)

rp1.Draw()

rp1.GetLowerRefYaxis().SetTitle("ratio")

rp1.GetUpperRefYaxis().SetTitle("entries")

c1.Update()