Matplotlib pie chart wedge transparency?

Question

I saw that matplotlib's pyplot.scatter() has an 'alpha' parameter that can be used to set the transparency of points. The pyplot.pie() doesn't have a similar parameter however. How can I set the transparency of certain wedges?

Answer 1

I found the answer while writing up this question and figured I'd post the solution for anyone who wants to know.

To set a wedge to be transparent:

import matplotlib.pyplot as plt

x  = [1,2,3,0.4,5]
alpha = 0.5
which_wedge = 4
n = plt.pie(x)
n[0][which_wedge].set_alpha(alpha)

If you want to only display a single wedge, use a loop:

for i in range(len(n[0])):
    n[0][i].set_alpha(0.0)
n[0][which_wedge].set_alpha(1.0)

Hope this helps someone! It can probably be used for pyplot.bar() too to hide certain bars.