Inserted Diagram

import matplotlib.pyplot as plt

fig = plt.figure()

X = [1, 2, 3, 4, 5, 6, 7]

Y = [1, 3, 4, 2, 5, 8, 6]

axes1 = fig.add_axes([0.1, 0.1, 0.9, 0.9]) # main axes

axes2 = fig.add_axes([0.2, 0.6, 0.4, 0.3]) # axes inside

# main figure

axes1.plot(X, Y, 'r')

axes1.set_xlabel('x')

axes1.set_ylabel('y')

axes1.set_title('title')

# insert

axes2.plot(Y, X, 'g')

axes2.set_xlabel('y')

axes2.set_ylabel('x')

axes2.set_title('title inside');