Get original values from cumulative sum

Question

>>> test.val.cumsum()
0    11
1    13
2    56
3    60
4    65
Name: val, dtype: int64

How do I get the original values from the cumulative sum? I will have to get [11,2,43,4,5]

Answer 1

You could use the diff() Series method (with fillna to replace the first value in the series):

>>> s = pd.Series([11, 13, 56, 60, 65])
>>> s.diff().fillna(s)
0    11
1     2
2    43
3     4
4     5
dtype: float64