graph.py

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#
# To see the output of this macro, click begin_html <a href="gif/graph.gif">here</a>. end_html
#

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' )

# TCanvas.Update() draws the frame, after which one can change it
c1.Update()
c1.GetFrame().SetFillColor( 21 )
c1.GetFrame().SetBorderSize( 12 )
c1.Modified()
c1.Update()