import numpy as np import matplotlib.pyplot as plt origin = 'lower' #origin = 'upper' delta = 0.025 x = y = np.arange(-3.0, 3.01, delta) X, Y = np.meshgrid(x, y) Z1 = plt.mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0) Z2 = plt.mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1) Z = 10 * (Z1 - Z2) nr, nc = Z.shape # put NaNs in one corner: Z[-nr//6:, -nc//6:] = np.nan # contourf will convert these to mask