我有一个关于每日用餐记录的数据集，如下所示：
Date Meals
04-02-2020 2
05-02-2020 3
06-02-2020 2
07-02-2020 3
08-02-2020 3
09-02-2020 2
10-02-2020 1
11-02-2020 3
12-02-2020 3
13-02-2020 1
14-02-2020 2
15-02-2020 1
16-02-2020 2
17-02-2020 2
18-02-2020 3
我想将记录的分布从每天转换为每周，以便结果如下：
Date (starting date of the week) Meals (average no. Meals in each week)
04-02-2020 2
11-02-2020 2
当我运行以下代码时：
df2=df.set_index('date') # note that Date was datetime datatype
Output = df2.resample('W',loffset=pd.offsets.timedelta(days=-6)).apply({'Snack' : 'mean'})
我得到了这个错误：
---------------------------------------------------------------------------
SpecificationError Traceback (most recent call last)
<ipython-input-1382-5715acb0763f> in <module>
----> 1 Output = df2.resample('W',loffset=pd.offsets.timedelta(days=-6)).apply({'Snack' : 'mean'})
~/opt/anaconda3/lib/python3.7/site-packages/pandas/core/resample.py in aggregate(self, func, *args, **kwargs)
279
280 self._set_binner()
--> 281 result, how = self._aggregate(func, *args, **kwargs)
282 if result is None:
283 how = func
~/opt/anaconda3/lib/python3.7/site-packages/pandas/core/base.py in _aggregate(self, arg, *args, **kwargs)
364 obj.columns.intersection(keys)
365 ) != len(keys):
--> 366 raise SpecificationError("nested renamer is not supported")
367
368 from pandas.core.reshape.concat import concat
SpecificationError: nested renamer is not supported
有人能帮忙吗？：(
谢谢Shosho
df2 = (df
.set_index('date')
.groupby(pd.Grouper(freq='W')
.sum()
)