content: """
  This example makes custom 'pie charts' as the markers for a scatter plotqu
  
  Thanks to Manuel Metz for the example
  """
  import math
  import numpy as np
  import matplotlib.pyplot as plt
  
  # first define the ratios
  r1 = 0.2      # 20%
  r2 = r1 + 0.4 # 40%
  
  # define some sizes of the scatter marker
  sizes = [60,80,120]
  
  # calculate the points of the first pie marker
  #
  # these are just the origin (0,0) +
  # some points on a circle cos,sin
  x = [0] + np.cos(np.linspace(0, 2*math.pi*r1, 10)).tolist()
  y = [0] + np.sin(np.linspace(0, 2*math.pi*r1, 10)).tolist()
  xy1 = list(zip(x,y))
  
  # ...
  x = [0] + np.cos(np.linspace(2*math.pi*r1, 2*math.pi*r2, 10)).tolist()
  y = [0] + np.sin(np.linspace(2*math.pi*r1, 2*math.pi*r2, 10)).tolist()
  xy2 = list(zip(x,y))
  
  x = [0] + np.cos(np.linspace(2*math.pi*r2, 2*math.pi, 10)).tolist()
  y = [0] + np.sin(np.linspace(2*math.pi*r2, 2*math.pi, 10)).tolist()
  xy3 = list(zip(x,y))
  
  
  fig, ax = plt.subplots()
  ax.scatter( np.arange(3), np.arange(3), marker=(xy1,0), s=sizes, facecolor='blue' )
  ax.scatter( np.arange(3), np.arange(3), marker=(xy2,0), s=sizes, facecolor='green' )
  ax.scatter( np.arange(3), np.arange(3), marker=(xy3,0), s=sizes, facecolor='red' )
  plt.show()
  