'Ungrouping a pandas dataframe after aggregation operation
I have used the "groupby" method on my dataframe to find the total number of people at each location.
To the right of the "sum" column, I need to add a column that lists all of the people's names at each location (ideally in separate rows, but a list would be fine too).
Is there a way to "ungroup" my dataframe again after having found the sum?
dataframe.groupby(by=['location'], as_index=False)['people'].agg('sum')
Solution 1:[1]
You can do two different things:
(1) Create an aggregate DataFrame using groupby.agg and calling appropriate methods. The code below lists all names corresponding to a location:
out = dataframe.groupby(by=['location'], as_index=False).agg({'people':'sum', 'name':list})
(2) Use groupby.transform to add a new column to dataframe that has the sum of people by location in each row:
dataframe['sum'] = dataframe.groupby(by=['location'])['people'].transform('sum')
Solution 2:[2]
I think you are looking for 'transform' ?
dataframe.groupby(by=['location'], as_index=False)['people'].transform('sum')
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | |
| Solution 2 | Daniel Weigel |