How to set opacity of background colour of graph with Matplotlib

Question

I've been playing around with Matplotlib and I can't figure out how to change the background colour of the graph, or how to make the background completely transparent.

Answer 1

If you just want the entire background for both the figure and the axes to be transparent, you can simply specify transparent=True when saving the figure with fig.savefig.

e.g.:

import matplotlib.pyplot as plt
fig = plt.figure()
plt.plot(range(10))
fig.savefig('temp.png', transparent=True)

If you want more fine-grained control, you can simply set the facecolor and/or alpha values for the figure and axes background patch. (To make a patch completely transparent, we can either set the alpha to 0, or set the facecolor to 'none' (as a string, not the object None!))

e.g.:

import matplotlib.pyplot as plt

fig = plt.figure()

fig.patch.set_facecolor('blue')
fig.patch.set_alpha(0.7)

ax = fig.add_subplot(111)

ax.plot(range(10))

ax.patch.set_facecolor('red')
ax.patch.set_alpha(0.5)

# If we don't specify the edgecolor and facecolor for the figure when
# saving with savefig, it will override the value we set earlier!
fig.savefig('temp.png', facecolor=fig.get_facecolor(), edgecolor='none')

plt.show()