代码运行之后：
C:\ProgramData\Anaconda3\lib\site-packages\ipykernel_launcher.py:35: FutureWarning: Sorting because non-concatenation axis is not aligned. A future version of pandas will change to not sort by default. To accept the future behavior, pass 'sort=False'. To retain the current behavior and silence the warning, pass 'sort=True'.
是说 pandas 这个包的行为将来会变化，你可以用 sort = False、True 来选择其中一种行为。