Clipping in Matplotlib. Why doesn't this work?

Question

I'm attempting to clip shapes like circles and ellipses using clipping in Matplotlib, but there must be something I am missing.. Why doesn't this clip the circle in half?:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Circle
from matplotlib.transforms import Bbox

clip_box = Bbox(((-2,-2),(2,0)))
circle = Circle((0,0),1,clip_box=clip_box,clip_on=True)

plt.axes().add_artist(circle)
plt.axis('equal')
plt.axis((-2,2,-2,2))
plt.show()

Answer 1

I do not know why your code does not work, however, the following snippet works as you expect.

From my undestanding, clip_on is not related to applying a given clipping to a shape but wether the shape should clip in the display area.

import matplotlib.pyplot as plt
from matplotlib.patches import Circle, Rectangle

rect = Rectangle((-2,-2),4,2, facecolor="none", edgecolor="none")
circle = Circle((0,0),1)

plt.axes().add_artist(rect)
plt.axes().add_artist(circle)

circle.set_clip_path(rect)

plt.axis('equal')
plt.axis((-2,2,-2,2))
plt.show()