Fit 1

Fit example.

Author: Wim Lavrijsen
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, June 22, 2021 at 08:30 AM.

In [ ]:
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

In [ ]:
fill = TFile( 'py-fillrandom.root' )

The function "ls()" lists the directory contents of this file

In [ ]:
fill.ls()

Get object "sqroot" from the file.

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sqroot = gROOT.FindObject( 'sqroot' )
sqroot.Print()

Now fit histogram h1f with the function sqroot

In [ ]:
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

In [ ]:
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

In [ ]:
from ROOT import gROOT 
gROOT.GetListOfCanvases().Draw()