A CHECKERBOARD IN MATPLOTLIB

Listing 5.12 displays the content of checkerboard1.py that illustrates how to display a checkerboard.

LISTING 5.12: checkerboard1.py

import matplotlib.pyplot as plt
from matplotlib import colors
import numpy as np

data = np.random.rand(10, 10) * 20

# create discrete colormap
cmap = colors.ListedColormap(['red', 'blue'])
bounds = [0,10,20]
norm = colors.BoundaryNorm(bounds, cmap.N)

fig, ax = plt.subplots()
ax.imshow(data, cmap=cmap, norm=norm)

# draw gridlines

ax.grid(which='major', axis='both', linestyle='-', color='k', linewidth=2)
ax.set_xticks(np.arange(-.5, 10, 1));
ax.set_yticks(np.arange(-.5, 10, 1));

plt.show()

Listing 5.12 defines the NumPy variable data that defines a 2D set of points with ten rows and ten columns. The Pyplot API plot() uses the data variable to display a colored grid-like pattern. Figure 5.9 displays a colored grid whose equations are contained in Listing 5.12.

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