python 画图

import matplotlib.pyplot as plt
L = [[2,2],[3,2],[1.75,1],[2, 1],[2.25, 1],[2.5, 1]]
plt.title('I am a scatter diagram')
plt.xlim(xmax = 7, xmin = 0)
plt.ylim(ymax = 7, ymin = 0)
plt.annotate("(1, 6)", xy = (1, 6),xytext = (2, 5), arrowprops = dict(facecolor = 'red',
             shrink = 0.1))
plt.xlabel('x')
plt.ylabel('y')
plt.plot(L,'ro')
plt.show()