Aggregated datetime64 column converted to float

[mattijohn]

See this Stackoverflow question

It appears that when grouping and then aggregating a datetime column the dtype converts to float

[lodagro]

this is what i get with master:

In [79]: dt
Out[79]: 
                           atn  file
datetime                            
2012-10-08 14:00:00  23.007462     1
2012-10-08 14:30:00  27.045666     1
2012-10-08 15:00:00  31.483825     1
2012-10-08 15:30:00  37.540651     2
2012-10-08 16:00:00  43.564573     2
2012-10-08 16:00:00  48.589852     2
2012-10-08 16:00:00  55.289452     2

In [80]: dt.reset_index().groupby(by="file").aggregate("first")
Out[80]: 
                datetime        atn
file                               
1    2012-10-08 14:00:00  23.007462
2    2012-10-08 15:30:00  37.540651

In [81]: dt.reset_index().groupby(by="file").aggregate("first").dtypes
Out[81]: 
datetime    datetime64[ns]
atn                float64

[wesm]

This was fixed in #2133

[mattijohn]

Thanks, sorry didn't notice it when I searched the issues list.