"""Simple matshow() example."""
import matplotlib.pyplot as plt
import numpy as np


def samplemat(dims):
    """Make a matrix with all zeros and increasing elements on the diagonal"""
    aa = np.zeros(dims)
    for i in range(min(dims)):
        aa[i, i] = i
    return aa

# Display 2 matrices of different sizes
dimlist = [(12, 12), (15, 35)]
for d in dimlist:
    plt.matshow(samplemat(d))

# Display a random matrix with a specified figure number and a grayscale
# colormap
plt.matshow(np.random.rand(64, 64), fignum=100, cmap=plt.cm.gray)

plt.show()