Set background color for subplot

Say I have an image made of 4 sub plots like so: import matplotlib.pyplot as plt import numpy as np ``` # Simple data to display in various forms x = np.linspace(0, 2 * np.pi, 400) y = np.sin(x ** 2) # Four axes, returned as a 2-d array f, axarr = plt.subplots(2, 2) axarr[0, 0].plot(x, y) axarr[0, 0].set_title('Axis [0,0]') axarr[0, 1].scatter(x, y) axarr[0, 1].set_title('Axis [0,1]') axarr[1, 0].plot(x, y ** 2) axarr[1, 0].set_title('Axis [1,0]') axarr[1, 1].scatter(x, y ** 2) axarr[1, 1].set_title('Axis [1,1]') # Fine-tune figure; hide x ticks for top plots and y ticks for right plots plt.setp([a.get_xticklabels() for a in axarr[0, :]], visible=False) plt.setp([a.get_yticklabels() for a in axarr[:, 1]], visible=False) plt.show() ``` which returns this: I want to add a grey background to one of this plots, say the bottom left one, since I like the way `R` makes some images look (see here for example). I haven't found an easy way to do this with `matplotlib`, am I missing something?