How to add a new column that includes sum consecutive values of other column?

Question

I am new to python. I want to create a column in pandas that includes the sum of consecutive values of a column. For example, let's assume we have the following table

id	A
1	21
2	32
3	55

And I want to have this table

id	A	New column
1	21	21
2	32	53
3	55	108

Any help will be appreciated.

Answer 1

This is called a cumulative sum. You can just set df["C"] = df["A"].cumsum() .

https://pandas.pydata.org/docs/reference/api/pandas.Series.cumsum.html