我正在使用熊猫0.16.2.这在我的大型数据集上具有更好的性能:

I'm using pandas 0.16.2. This has better performance on my large dataset:

data.groupby(data.date.dt.year)

使用dt选项并玩弄weekofyear，dayofweek等变得容易得多.

Using the dt option and playing around with weekofyear, dayofweek etc. becomes far easier.