>>> """
===================================
Scatter plot with pie chart markers
===================================

This example makes custom 'pie charts' as the markers for a scatter plot.

Thanks to Manuel Metz for the example.
"""
... 
... 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 = np.array([60, 80, 120])
... 
... # calculate the points of the first pie marker
... # these are just the origin (0, 0) + some (cos, sin) points on a circle
... x1 = np.cos(2 * np.pi * np.linspace(0, r1))
... y1 = np.sin(2 * np.pi * np.linspace(0, r1))
... xy1 = np.row_stack([[0, 0], np.column_stack([x1, y1])])
... s1 = np.abs(xy1).max()
... 
... x2 = np.cos(2 * np.pi * np.linspace(r1, r2))
... y2 = np.sin(2 * np.pi * np.linspace(r1, r2))
... xy2 = np.row_stack([[0, 0], np.column_stack([x2, y2])])
... s2 = np.abs(xy2).max()
... 
... x3 = np.cos(2 * np.pi * np.linspace(r2, 1))
... y3 = np.sin(2 * np.pi * np.linspace(r2, 1))
... xy3 = np.row_stack([[0, 0], np.column_stack([x3, y3])])
... s3 = np.abs(xy3).max()
... 
... fig, ax = plt.subplots()
... ax.scatter(range(3), range(3), marker=xy1, s=s1**2 * sizes, facecolor='blue')
... ax.scatter(range(3), range(3), marker=xy2, s=s2**2 * sizes, facecolor='green')
... ax.scatter(range(3), range(3), marker=xy3, s=s3**2 * sizes, facecolor='red')
... 
... plt.show()
... 
... #############################################################################
... #
... # .. admonition:: References
... #
... #    The use of the following functions, methods, classes and modules is shown
... #    in this example:
... #
... #    - `matplotlib.axes.Axes.scatter` / `matplotlib.pyplot.scatter`
...