Description
Bug summary
Possible bug or maybe a usage issue following some recent updates...
In short, it used to be possible to set the hatch color for each filled contour area to a different color by iterating over the collections and then setting the edgecolor for each, but that's no longer the case with Matplotlib 3.10 and the removal of collections.
I've been trying to find a workaround after the recent updates, but am struggling a bit. Using set_edgecolors only sets a single hatch color for all filled contours (which seems unexpected based upon the docs and like a potential bug) and rcParams['hatch.color'] also just sets a single color (less suprising).
It's entirely possible I'm missing something here, but didn't see much in the docs to help either.
Code for reproduction
# The new approach I was hoping would work, but got unexpected results from
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()
fig1, ax1 = plt.subplots()
cs = ax1.contourf(x, y, z, hatches=['-', '/', '\\', '//'],
cmap='gray', extend='both', alpha=0.5)
cs.set_edgecolors(["blue","grey","yellow","red"])
fig1.colorbar(cs)
# The older approach that now fails with Matplotlib 3.10
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()
fig1, ax1 = plt.subplots()
cs = ax1.contourf(x, y, z, hatches=['-', '/', '\\', '//'],
cmap='gray', extend='both', alpha=0.5)
colors = ["blue","grey","yellow","red"]
for i, collection in enumerate(cs.collections):
collection.set_edgecolor(colors[i % len(colors)])
fig1.colorbar(cs)Actual outcome
Expected outcome
Additional information
No response
Operating system
OS/X
Matplotlib Version
3.9.2
Matplotlib Backend
'module://matplotlib_inline.backend_inline'
Python version
3.11.7
Jupyter version
4.0.9
Installation
conda