How can I set different opacity of edgecolor and facecolor of a patch in Matplotlib

Question

I am trying to plot a set of triangles with different orientations and sizes. The inner overlapped shape is what i wanted, which is the darkest area. But when I set opacity (alpha) in mpatches.RegularPolygon, the edges become transparent too. How can I solve this problem? Thank you!

Answer 1

You should perhaps post some code to make your meaning clear, but from what I understand, you could set the facecolor and edgecolor separately as (R,G,B,alpha) tuples and set alpha for the edgecolor equal to 1 to make it opaque if that's what you want. For example,

import matplotlib.pyplot as plt
from matplotlib.patches import Polygon

fig = plt.figure()
ax = fig.add_subplot(111, aspect='equal')

triangle1 = Polygon(((0.05,0.1), (0.396,0.1), (0.223, 0.38)),
                    fc=(1,0,0,0.5), ec=(0,0,0,1), lw=2)
triangle2 = Polygon(((0.2,0.2), (0.5,0.4), (0.3, 0.6)),
                    fc=(1,0,0,0.5), ec=(0,0,0,1), lw=2)

ax.add_artist(triangle1)
ax.add_artist(triangle2)

plt.show()