import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches

x = y = np.arange(-3.0, 3.01, 0.025)
X, Y = np.meshgrid(x, y)
Z1 = np.exp(-X**2 - Y**2)
Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2)
Z = (Z1 - Z2) * 2

fig, ax = plt.subplots()
patch = mpatches.RegularPolygon((0, 0), 5, radius=2,
                                transform=ax.transData)
ax.contourf(X, Y, Z, clip_path=patch)

plt.show()