import matplotlib as mpl
from matplotlib.patches import Rectangle

fig, ax = plt.subplots()

# In this case, hatchcolor is orange
patch1 = Rectangle((0.1, 0.1), 0.3, 0.3, edgecolor='red', linewidth=2,
                   hatch='//', hatchcolor='orange')
ax.add_patch(patch1)

# When hatchcolor is not specified, it matches edgecolor
# In this case, hatchcolor is green
patch2 = Rectangle((0.6, 0.1), 0.3, 0.3, edgecolor='green', linewidth=2,
                   hatch='//', facecolor='none')
ax.add_patch(patch2)

# If both hatchcolor and edgecolor are not specified
# it will default to the 'patch.edgecolor' rcParam, which is black by default
# In this case, hatchcolor is black
patch3 = Rectangle((0.1, 0.6), 0.3, 0.3, hatch='//')
ax.add_patch(patch3)

# When using `hatch.color` in the `rcParams`
# edgecolor will now not overwrite hatchcolor
# In this case, hatchcolor is black
with plt.rc_context({'hatch.color': 'black'}):
    patch4 = Rectangle((0.6, 0.6), 0.3, 0.3, edgecolor='blue', linewidth=2,
                       hatch='//', facecolor='none')

# hatchcolor is black (it uses the `hatch.color` rcParam value)
patch4.set_edgecolor('blue')
# hatchcolor is still black (here, it does not update when edgecolor changes)
ax.add_patch(patch4)

ax.annotate("hatchcolor = 'orange'",
            xy=(.5, 1.03), xycoords=patch1, ha='center', va='bottom')
ax.annotate("hatch color unspecified\nedgecolor='green'",
            xy=(.5, 1.03), xycoords=patch2, ha='center', va='bottom')
ax.annotate("hatch color unspecified\nusing patch.edgecolor",
            xy=(.5, 1.03), xycoords=patch3, ha='center', va='bottom')
ax.annotate("hatch.color='black'",
            xy=(.5, 1.03), xycoords=patch4, ha='center', va='bottom')