In Python, how do you change the size of an already created figure drawn with Matplotlib?

The simplest way to change the size of an existing Matplotlib figure is to use the method set_size_inches():

import matplotlib.pyplot as plt
plt.plot ([1,9,2,8,3,7,4,6,5,5])

# Set figure size in inches
fig = plt.gcf()
fig.set_size_inches(20, 4)

The above code should display something like: