Fill area of chart using matplotlib in python 

import matplotlib.pyplot as plt
y = [1,2,3,4,5,6]
x = [1,2,1,2,3,2]
x1 = [0,1,0,1,2,1]
x2 = [2,3,2,3,4,3]
plt.plot(x,y)
plt.fill_betweenx(y,x1,x2, color="lightblue", alpha=0.5)
plt.axvspan(2,3, color="red", alpha=0.2)
plt.axhspan(3,5, color="green", alpha=0.2)
plt.show()

Наука