soungalo soungalo - 3 months ago 8
Python Question

How to sum all values with index greater than X?

Let's say I have this series:

>>> s = pd.Series({1:10,2:5,3:8,4:12,5:7,6:3})
>>> s
1 10
2 5
3 8
4 12
5 7
6 3


I want to sum all the values for which the index is greater than X. So if e.g. X = 3, I want to get this:

>>> X = 3
>>> s.some_magic(X)
1 10
2 5
3 8
>3 22


I managed to do it in this rather clumsy way:

lt = s[s.index.values <= 3]
gt = s[s.index.values > 3]
gt_s = pd.Series({'>3':sum(gt)})
lt.append(gt_s)


and got the desired result, but I believe there should be an easier and more elegant way... or is there?

Answer
s.groupby(np.where(s.index > 3, '>3', s.index)).sum()

Or,

s.groupby(s.index.to_series().mask(s.index > 3, '>3')).sum()
Out: 
1     10
2      5
3      8
>3    22
dtype: int64