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 points on a circle cos,sin
x = [0] + np.cos(np.linspace(0, 2 * np.pi * r1, 10)).tolist()
y = [0] + np.sin(np.linspace(0, 2 * np.pi * r1, 10)).tolist()
xy1 = np.column_stack([x, y])
s1 = np.abs(xy1).max()

x = [0] + np.cos(np.linspace(2 * np.pi * r1, 2 * np.pi * r2, 10)).tolist()
y = [0] + np.sin(np.linspace(2 * np.pi * r1, 2 * np.pi * r2, 10)).tolist()
xy2 = np.column_stack([x, y])
s2 = np.abs(xy2).max()

x = [0] + np.cos(np.linspace(2 * np.pi * r2, 2 * np.pi, 10)).tolist()
y = [0] + np.sin(np.linspace(2 * np.pi * r2, 2 * np.pi, 10)).tolist()
xy3 = np.column_stack([x, y])
s3 = np.abs(xy3).max()

fig, ax = plt.subplots()
ax.scatter(range(3), range(3), marker=(xy1, 0),
           s=s1 ** 2 * sizes, facecolor='blue')
ax.scatter(range(3), range(3), marker=(xy2, 0),
           s=s2 ** 2 * sizes, facecolor='green')
ax.scatter(range(3), range(3), marker=(xy3, 0),
           s=s3 ** 2 * sizes, facecolor='red')

plt.show()