解决问题
No handles with labels found to put in legend.
解决思路
matplotlib.pyplot .plot 时，没有设置参数label="xx"
解决方法
import matplotlib.pyplot as plt
plt.plot(x, y label='上海')
大功告成！
No handles with labels found to put in legend.
matplotlib.pyplot .plot 时，没有设置参数label="xx"
import matplotlib.pyplot as plt
plt.plot(x, y label='上海')
大功告成！
