Perhaps you can try to use Py-Plot's object-oriented environment, by substituting as follows:

import matplotlib.pyplot as plt
import numpy as np

xs = np.array([100, 500])
ys = np.array([300, 800])

fig, ax = plt.subplots() ax.plot(xs,ys)

I dont know if it will help you, but I have also had trouble with my graphs coming out all ascii-art like.