Fit example.
Author: Wim Lavrijsen
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Thursday, January 21, 2021 at 10:22 AM.
from os import path
from ROOT import TCanvas, TFile, TPaveText
from ROOT import gROOT, gBenchmark
c1 = TCanvas( 'c1', 'The Fit Canvas', 200, 10, 700, 500 )
c1.SetGridx()
c1.SetGridy()
c1.GetFrame().SetFillColor( 21 )
c1.GetFrame().SetBorderMode(-1 )
c1.GetFrame().SetBorderSize( 5 )
gBenchmark.Start( 'fit1' )
We connect the ROOT file generated in a previous tutorial
fill = TFile( 'py-fillrandom.root' )
The function "ls()" lists the directory contents of this file
fill.ls()
Get object "sqroot" from the file.
sqroot = gROOT.FindObject( 'sqroot' )
sqroot.Print()
Now fit histogram h1f with the function sqroot
h1f = gROOT.FindObject( 'h1f' )
h1f.SetFillColor( 45 )
h1f.Fit( 'sqroot' )
We now annotate the picture by creating a PaveText object and displaying the list of commands in this macro
fitlabel = TPaveText( 0.6, 0.3, 0.9, 0.80, 'NDC' )
fitlabel.SetTextAlign( 12 )
fitlabel.SetFillColor( 42 )
fitlabel.ReadFile(path.join(str(gROOT.GetTutorialDir()), 'pyroot', 'fit1_py.py'))
fitlabel.Draw()
c1.Update()
gBenchmark.Show( 'fit1' )
Draw all canvases
from ROOT import gROOT
gROOT.GetListOfCanvases().Draw()