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()