"No numeric types to aggregate" after groupby and mean

your data1 is of object (string) dtype:

In [396]: datedatF.dtypes
Out[396]:
data1            object   # <--- NOTE!
key1     datetime64[ns]
key2              int64
dtype: object

so try this:

In [397]: datedatF.assign(data1=pd.to_numeric(datedatF['data1'], errors='coerce')) \
                  .groupby('key2')['data1'].mean()
Out[397]:
key2
2015001    1.3
Name: data1, dtype: float64

You data1 type in your df is object , we need adding pd.to_numeric

datedatF.dtypes
Out[39]: 
data1            object
key1     datetime64[ns]
key2              int64
dtype: object
grouped2=pd.to_numeric(datedatF['data1']).groupby(datedatF['key2'])
grouped2.mean()
Out[41]: 
key2
2015001    1.3
Name: data1, dtype: float64