"""

=========================

Frontpage contour example

=========================

This example reproduces the frontpage contour example.

"""

import matplotlib.pyplot as plt

import numpy as np

from matplotlib import cm

extent = (-3, 3, -3, 3)

delta = 0.5

x = np.arange(-3.0, 4.001, delta)

y = np.arange(-4.0, 3.001, delta)

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

norm = cm.colors.Normalize(vmax=abs(Z).max(), vmin=-abs(Z).max())

fig, ax = plt.subplots()

cset1 = ax.contourf(

X, Y, Z, 40,

norm=norm)

ax.set_xlim(-2, 2)

ax.set_ylim(-2, 2)

ax.set_xticks([])

ax.set_yticks([])

fig.savefig("contour_frontpage.png", dpi=25) # results in 160x120 px image

plt.show()