GroupBy.count() returns the grouping column as both index and column #5610
Description
GroupBy.count() (with the default as_index=True) return the grouping column both as index and as column, while other methods as first and sum keep it only as the index (which is most logical I think). This seems a minor inconsistency to me:
In [41]: data = pd.DataFrame({'name' : ['a', 'a', 'b', 'd'], 'counts' : [3,4,3,2]})
In [42]: data
Out[42]:
counts name
0 3 a
1 4 a
2 3 b
3 2 d
In [43]: g = data.groupby('name')
In [45]: g.count()
Out[45]:
counts name
name
a 2 2
b 1 1
d 1 1
In [46]: g.first()
Out[46]:
counts
name
a 3
b 3
d 2
In [47]: g.sum()
Out[47]:
counts
name
a 7
b 3
d 2