import matplotlib.pyplot as plt
import numpy as np

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

fg, ax = plt.subplots(1, 1)

r = 2.
yoff = -1

x = np.arange(-1., 1.05, 0.05)
y = np.sqrt(r - x ** 2) + yoff

ax.fill_between(x, y, 0)
ax.axis([-2, 2, -2, 2])
ax.set_aspect("equal")

fg.canvas.draw()

plt.show()