Hatched contourf plots in matplolib

hatched.py

# From https://github.com/matplotlib/matplotlib/issues/2789/#issuecomment-604599060

# Content as in example
# ------------------------------
import matplotlib.pyplot as plt
import numpy as np
# invent some numbers, turning the x and y arrays into simple
# 2d arrays, which make combining them together easier.
x = np.linspace(-3, 5, 150).reshape(1, -1)
y = np.linspace(-3, 5, 120).reshape(-1, 1)
z = np.cos(x) + np.sin(y)

# we no longer need x and y to be 2 dimensional, so flatten them.
x, y = x.flatten(), y.flatten()

# a plot of hatches without color with a legend
plt.figure()
n_levels = 6
plt.contour(x, y, z, n_levels, colors='black', linestyles='-')
cs = plt.contourf(
    x, y, z, n_levels, colors='none',
    hatches=['.', '/', '\\', None, '\\\\', '*'],
    extend='lower',
)

plt.title('Before')
plt.savefig("mpl_test_before.jpeg")

# ------------------------------
# New bit here that handles changing the color of hatches
colors = ['maroon', 'red', 'darkorange', 'gold', 'forestgreen',
          'darkturquoise', 'dodgerblue', 'darkviolet']
# For each level, we set the color of its hatch 
for i, collection in enumerate(cs.collections):
    collection.set_edgecolor(colors[i % len(colors)])
# Doing this also colors in the box around each level
# We can remove the colored line around the levels by setting the linewidth to 0
for collection in cs.collections:
    collection.set_linewidth(0.)
# ------------------------------

plt.title('After')
plt.savefig("mpl_test_after.jpeg")