import matplotlib.pyplot as plt
import numpy as np
from matplotlib.patches import Ellipse

NUM = 250

ells = [Ellipse(xy=np.random.rand(2) * 10,
    width=np.random.rand(), height=np.random.rand(),
    angle=np.random.rand() * 360)
  for i in range(NUM)]

fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})
for e in ells:
 ax.add_artist(e)
 e.set_clip_box(ax.bbox)
 e.set_alpha(np.random.rand())
 e.set_facecolor(np.random.rand(3))

ax.set_xlim(0, 10)
ax.set_ylim(0, 10)

plt.show()