import matplotlib.pyplot as plt
import math
x_list = range(1,20)
y_list = range(1,20)
# draw
plt.figure(figsize=(13, 7))
plt.plot(x_list, y_list, color="red", linewidth=3)
plt.xlabel("")
plt.ylabel("R")
plt.title(u"x x")
plt.legend((u"图例",))
plt.ylim(0, 30)
plt.legend()
plt.show()