examples/graphs/washboard.py

   1 # contributed by Sigmund Kohler
   2
   3 from math import pi, cos
   4 from pyx import *
   5 from pyx.deco import barrow, earrow
   6 from pyx.style import linewidth, linestyle
   7 from pyx.graph import graphxy
   8 from pyx.graph.axis import linear
   9 from pyx.graph.axis.painter import regular
  10 from pyx.graph.style import line
  11 from pyx.graph.data import function
  12
  13 mypainter = regular(basepathattrs=[earrow.normal], titlepos=1)
  14 def mycos(x): return -cos(x)+.10*x
  15
  16 g = graphxy(height=5, x2=None, y2=None,
  17             x=linear(min=-2.5*pi, max=3.3*pi, parter=None,
  18                       painter=mypainter, title=r"$\delta\phi$"),
  19             y=linear(min=-2.3, max=2, painter=None))
  20 g.plot(function("y(x)=mycos(x)", context=locals()),
  21        [line(lineattrs=[linewidth.Thick])])
  22 g.finish()
  23
  24 x1, y1 = g.pos(-pi+.1, mycos(-pi+.1))
  25 x2, y2 = g.pos(-.1, mycos(-.1))
  26 x3, y3 = g.pos(pi+.1, mycos(pi+.1))
  27
  28 g.stroke(path.line(x1-.5, y1, x1+.5, y1), [linestyle.dashed])
  29 g.stroke(path.line(x1-.5, y3, x3+.5, y3), [linestyle.dashed])
  30 g.stroke(path.line(x2-.5, y2, x3+.5, y2), [linestyle.dashed])
  31 g.stroke(path.line(x1, y1, x1, y3), [barrow.normal, earrow.normal])
  32 g.stroke(path.line(x3, y2, x3, y3), [barrow.normal, earrow.normal])
  33 g.text(x1+.2, 0.5*(y1+y3), r"$2\pi\gamma k\Omega$", [text.vshift.middlezero])
  34 g.text(x1-.6, y1-.1, r"$E_{\rm b}$", [text.halign.right])
  35 g.text(x3+.15, y2+.20, r"$2J_k(\varepsilon/\Omega)+\pi\gamma k\Omega$")
  36
  37 g.writeEPSfile("washboard")
  38 g.writePDFfile("washboard")