examples/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 fline = g.plot(graph.data.function("y=sin(1.0/(x**2+0.02122))", points=1000))
  10 horiz = g.plot(graph.data.function("y=0.5*x", points=2))
  11 g.finish()
  12
  13 # convert paths to normpaths (for efficiency reasons only)
  14 fline = fline.path.normpath()
  15 horiz = horiz.path.normpath()
  16 # intersect the lines
  17 splith, splitf = horiz.intersect(fline)
  18
  19 # create gray area (we do not use simple clipping)
  20 area = horiz.split([splith[0]])[0]
  21 for i in range(0, len(splith)-2, 2):
  22     area = area.joined(fline.split([splitf[i], splitf[i+1]])[1])
  23     area = area.joined(horiz.split([splith[i+1], splith[i+2]])[1])
  24 area = area.joined(fline.split([splitf[-2], splitf[-1]])[1])
  25 area = area.joined(horiz.split([splith[-1]])[1])
  26 area[-1].append(path.normline(*(area[-1].end_pt() + g.vpos_pt(1, 0))))
  27 area[-1].append(path.normline(*(area[-1].end_pt() + g.vpos_pt(0, 0))))
  28 area[-1].close()
  29
  30 c = canvas.canvas()
  31
  32 # draw first the area, then the function
  33 c.fill(area, [color.gray(0.6)])
  34 c.stroke(fline, [style.linewidth.Thick, style.linejoin.round])
  35
  36 c.writeEPSfile("partialfill")