单项选择题
print(frame['height'].resample('M', kind='period').mean())
写成分组的方法中,错误的是:
A、print(frame['height'].groupby(frame.index.dt.month).mean())
B、print(frame['height'].groupby(frame.index.month).mean())
C、print(frame['height'].groupby(frame.index.to_period(freq='M')).mean())
D、print(frame.groupby(frame.index.to_period(freq='M'))['height'].mean())