Python, is there a function that give me the cumulate sum?

Question

I have the following list value:

iva_versamenti_totale={'Liquidazione IVA': [sum(t) for t in zip(*iva_versamenti.values())],}

I want to obtain about the iva_versamenti_totale variable the following sum:

p0, p1+p0, p2+p1, p3+p2 and so on...

Ad example:

iva_versamenti_totale = {'Liquidazione IVA': [1,2,3,4,5],}
result={'Totals': [1,3,5,7,9],}

EDIT

I have tried the following code:

iva_versamenti_totale = [1,2,3,4,5]

results = [*map(sum, zip(iva_versamenti_totale , [0]+iva_versamenti_totale ))]

But if I try

iva_versamenti_totale = [1,0,0,0]

I want to obtain [1,1,1,1], instead I obtain [1,1,0,0]

Better duplicate target: https://stackoverflow.com/questions/3849625/pairwise-traversal-of-a-list-or-tuple — timgeb, May 08 '20 at 08:37
Does this answer your question? [pairwise traversal of a list or tuple](https://stackoverflow.com/questions/3849625/pairwise-traversal-of-a-list-or-tuple) — Brown Bear, May 08 '20 at 08:42

score 1 · Accepted Answer · answered May 08 '20 at 08:53

1

Another version:

l = [1,2,3,4,5]

s = [*map(sum, zip(l, [0]+l))]

print(s)

Prints:

[1, 3, 5, 7, 9]

answered May 08 '20 at 08:53

Andrej Kesely

I have solved it with your answer. Just a last questio: if I want to set a filter that set at zero the negative value? Ad example if my print is `[ 1, 3, 5, -3 ]`give me `[ 1, 3, 5, 0 ] ?? – May 08 '20 at 09:15
@Jfix91 if you want to set negative values in list to `0` you can do for example `print([max(0, v) for v in [1, 3, 5, -3]])` – Andrej Kesely May 08 '20 at 10:08
oKEY Thanks. I have noticed that your code don't save the values of previous i. Ad example: if I have `[1,0,0,0,0]` the result may be `[1,1,1,1,1]` instead [1,1,0,0,0] – May 08 '20 at 10:46

DARK_C0D3R · Answer 2 · 2020-05-08T08:40:19.033

0

You can try like :

a =  [1,2,3,4,5]
[a[i]+a[i-1] if i!=0 else a[i] for i in range(len(a))]

edited May 08 '20 at 08:40

answered May 08 '20 at 08:35

DARK_C0D3R

2 Answers2