how to subtract next values in one columns?

Question

gaess, I Want to subtract the previous values and next value (previous - next) in one columns on Python dataframe. The example and the output like this :

This is the one column dataframe:

  | Gross_reserve|
  | ------------ |
0 | 1.202.170,21 | 
1 | 1.190.721,39 | 
2 | 1.179.354,33 | 
3 | 1.131.377,18 | 
4 |     ...      |

And then the output i want is make a new columns called "cf_res_g" with the value like this :

  | Gross_reserve| cf_res_g |
  | ------------ | -------- |
0 | 1.202.170,21 | 11.448,82|
1 | 1.190.721,39 | 11.367,06|
2 | 1.179.354,33 | 47.997,16|
3 | 1.131.377,18 |  ...     |
4 |     ...      |  ...     |

so, if we do calculation is like this: index[0] - index[1], index[1] - index[2], etc

The input and the output looks very similar, can you please validate that they are correct? — Tom Ron, Jan 04 '23 at 11:28
Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. — Community, Jan 04 '23 at 11:30
@TomRon sorry i got error when i want to write the problem, i already fix it. Thankyou — Zefanya Simijaya, Jan 04 '23 at 11:42

score -1 · Answer 1 · answered Jan 04 '23 at 11:40

-1

I think you are asking for a diff: pandas.DataFrame.diff.

answered Jan 04 '23 at 11:40

Mahmoud

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I already use diff but the output in index[0] is NaN whereas i want the value in the index[0] is 11.448,82 like the example i made – Zefanya Simijaya Jan 04 '23 at 11:49
`diff()` accepts a a period parameter which can be negative. So try using `diff(-1)` – user19077881 Jan 04 '23 at 12:12

how to subtract next values in one columns?

1 Answers1