Sum up column values in Pandas DataFrame

Question

In a pandas DataFrame, is it possible to collapse columns which have identical values, and sum up the values in another column?

Code

Answer 1

This is a job for groupby:

>>> df.groupby(["score", "type"]).sum()
                        count
score    type                
9.397000 advanced  537.331573
9.397995 advanced    9.641728
9.397996 newbie      0.100000
9.399900 expert     19.6541374
>>> df.groupby(["score", "type"], as_index=False).sum()
      score      type       count
0  9.397000  advanced  537.331573
1  9.397995  advanced    9.641728
2  9.397996    newbie    0.100000
3  9.399900    expert   19.654137