>>> """
=========================
3D surface (checkerboard)
=========================

Demonstrates plotting a 3D surface colored in a checkerboard pattern.
"""
... 
... import matplotlib.pyplot as plt
... from matplotlib.ticker import LinearLocator
... import numpy as np
... 
... 
... ax = plt.figure().add_subplot(projection='3d')
... 
... # Make data.
... X = np.arange(-5, 5, 0.25)
... xlen = len(X)
... Y = np.arange(-5, 5, 0.25)
... ylen = len(Y)
... X, Y = np.meshgrid(X, Y)
... R = np.sqrt(X**2 + Y**2)
... Z = np.sin(R)
... 
... # Create an empty array of strings with the same shape as the meshgrid, and
... # populate it with two colors in a checkerboard pattern.
... colortuple = ('y', 'b')
... colors = np.empty(X.shape, dtype=str)
... for y in range(ylen):
...     for x in range(xlen):
...         colors[y, x] = colortuple[(x + y) % len(colortuple)]
... 
... # Plot the surface with face colors taken from the array we made.
... surf = ax.plot_surface(X, Y, Z, facecolors=colors, linewidth=0)
... 
... # Customize the z axis.
... ax.set_zlim(-1, 1)
... ax.zaxis.set_major_locator(LinearLocator(6))
... 
... plt.show()
...