Graph

A Simple Graph 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 10:23 AM.

In [1]:
from __future__ import print_function
from ROOT import TCanvas, TGraph
from ROOT import gROOT
from math import sin
from array import array


c1 = TCanvas( 'c1', 'A Simple Graph Example', 200, 10, 700, 500 )

c1.SetFillColor( 42 )
c1.SetGrid()

n = 20
x, y = array( 'd' ), array( 'd' )

for i in range( n ):
   x.append( 0.1*i )
   y.append( 10*sin( x[i]+0.2 ) )
   print(' i %i %f %f ' % (i,x[i],y[i]))

gr = TGraph( n, x, y )
gr.SetLineColor( 2 )
gr.SetLineWidth( 4 )
gr.SetMarkerColor( 4 )
gr.SetMarkerStyle( 21 )
gr.SetTitle( 'a simple graph' )
gr.GetXaxis().SetTitle( 'X title' )
gr.GetYaxis().SetTitle( 'Y title' )
gr.Draw( 'ACP' )

Welcome to JupyROOT 6.23/01
 i 0 0.000000 1.986693 
 i 1 0.100000 2.955202 
 i 2 0.200000 3.894183 
 i 3 0.300000 4.794255 
 i 4 0.400000 5.646425 
 i 5 0.500000 6.442177 
 i 6 0.600000 7.173561 
 i 7 0.700000 7.833269 
 i 8 0.800000 8.414710 
 i 9 0.900000 8.912074 
 i 10 1.000000 9.320391 
 i 11 1.100000 9.635582 
 i 12 1.200000 9.854497 
 i 13 1.300000 9.974950 
 i 14 1.400000 9.995736 
 i 15 1.500000 9.916648 
 i 16 1.600000 9.738476 
 i 17 1.700000 9.463001 
 i 18 1.800000 9.092974 
 i 19 1.900000 8.632094

TCanvas.Update() draws the frame, after which one can change it

In [2]:
c1.Update()
c1.GetFrame().SetFillColor( 21 )
c1.GetFrame().SetBorderSize( 12 )
c1.Modified()
c1.Update()

If the graph does not appear, try using the "i" flag, e.g. "python3 -i graph.py" This will access the interactive mode after executing the script, and thereby persist long enough for the graph to appear.

Draw all canvases

In [3]:
from ROOT import gROOT 
gROOT.GetListOfCanvases().Draw()