gallery/graphs/partialfill.py

   1 # contributed by Michael Schindler
   2
   3 from pyx import *
   4
   5 # get the lines from the graph
   6 xax = graph.axis.linear(min=-1, max=1.0, painter=None)
   7 yax = graph.axis.linear(min=-1.3, max=1.3, painter=None)
   8 g = graph.graphxy(width=10, ratio=2, x=xax, y=yax)
   9 pifline = g.plot(graph.data.function("y(x)=sin(1.0/(x**2+0.02122))", points=1000))
  10 pihoriz = g.plot(graph.data.function("y(x)=0.5*x", points=2))
  11 g.finish()
  12
  13 # fetch path from info returned by plot method of graph
  14 fline = pifline.path
  15 horiz = pihoriz.path
  16
  17 # intersect the lines
  18 splith, splitf = horiz.intersect(fline)
  19
  20 # create gray area (we do not use simple clipping)
  21 area = horiz.split([splith[0]])[0]
  22 for i in range(0, len(splith)-2, 2):
  23     area = area.joined(fline.split([splitf[i], splitf[i+1]])[1])
  24     area = area.joined(horiz.split([splith[i+1], splith[i+2]])[1])
  25 area = area.joined(fline.split([splitf[-2], splitf[-1]])[1])
  26 area = area.joined(horiz.split([splith[-1]])[1])
  27 area.append(path.lineto(*g.vpos(1, 0)))
  28 area.append(path.lineto(*g.vpos(0, 0)))
  29 area.append(path.closepath()) # not really needed (filling closes automatically)
  30
  31 c = canvas.canvas()
  32
  33 # draw first the area, then the function
  34 c.fill(area, [color.gray(0.6)])
  35 c.stroke(fline, [style.linewidth.Thick, style.linejoin.round])
  36
  37 c.writeEPSfile("partialfill")
  38 c.writePDFfile("partialfill")