CODEWITHSUNDEEP
pythonpandas
mikebmassey
mikebmassey

Reputation: 8584

Pandas Groupby - naming aggregate output column

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.

Upvotes: 6

Views: 5865

Answers (2)

Alexander
Alexander

Reputation: 109546

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})

Upvotes: 5

bcollins
bcollins

Reputation: 3459

I like @Alexander answer, but there is also add_prefix:

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

Upvotes: 5

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