Pandas Groupby - naming aggregate output column

Question

I have a pandas groupby command which looks like this:

df.groupby(['year', 'month'], as_index=False).agg({'users':sum})

Is there a way I can name the agg output something other than 'users' during the groupby command? For example, what if I wanted the sum of users to be total_users? I could rename the column after the groupby is complete, but wonder if there is another way.

Answer 1

Per the docs :

If a dict is passed, the keys will be used to name the columns. Otherwise the function's name (stored in the function object) will be used.

In [58]: grouped['D'].agg({'result1' : np.sum, ....:
'result2' : np.mean})

In your case:

df.groupby(['year', 'month'], as_index=False).users.agg({'total_users': np.sum})

Answer 2

我喜欢@Alexander的答案，但也有add_prefix ：

df.groupby(['year','month']).agg({'users':sum}).add_prefix('total_')