Add numbers of lists to the first number of the list

Question

I have the following list:

list_1 = [2.03898103, 2.23708741, 1.68221573, 1.12352885, 0.56227805]

And I want to add the numbers to the first number into the new list like this:

list_2 = []
list_2[0] = list_1[0]
list_2[1] = list_1[0] + list_1[1]
list_2[2] = list_1[0] + list_1[1] + list_1[2]
list_2[3] = list_1[0] + list_1[1] + list_1[2] + list_1[3]
list_2[4] = list_1[0] + list_1[1] + list_1[2] + list_1[3] + list_1[4]

How can I make this with a for loop or something more practical?

score 2 · Answer 1 · answered Apr 27 '21 at 16:51

2

Just in case you want a short answer, you can also use generators:

list_2 = [sum(list_1[:(i+1)]) for i in range(len(list_1))]

answered Apr 27 '21 at 16:51

Seeing Prorok

21
4

woow ! thanks a lot – Zaid Khalil Apr 27 '21 at 17:03

score 1 · Accepted Answer · answered Apr 27 '21 at 16:43

You can use itertools.accumulate:

from itertools import accumulate

list_1 = [2.03898103, 2.23708741, 1.68221573, 1.12352885, 0.56227805]
list_2 = list(accumulate(list_1))
print(list_2)

Prints:

[2.03898103, 4.2760684399999995, 5.95828417, 7.08181302, 7.64409107]

score 1 · Answer 3 · answered Apr 27 '21 at 16:54

1

list_1 = [2.03898103, 2.23708741, 1.68221573, 1.12352885, 0.56227805]
list_2 = []
j = 0.
for i in range(0,len(list_1)):
    j = j + list_1[i]
    list_2.append(j)
print(list_2)

answered Apr 27 '21 at 16:54

Alex

11
2

thank you, you solved for me another issue indirect. wow – Zaid Khalil Apr 27 '21 at 17:05
@ZaidKhalil for a simpler approach, as this list is only formed by floats I would recomend using the cumsum() function from NumPy – Alex Apr 27 '21 at 17:10

score 1 · Answer 4 · edited Jul 20 '21 at 08:37

1

You've tagged as NumPy in your question, so just use numpy.cumsum:

>>> import numpy as np
>>> list_1 = np.array([2.03898103, 2.23708741, 1.68221573, 1.12352885, 0.56227805])
>>> np.cumsum(list_1)
array([2.03898103, 4.27606844, 5.95828417, 7.08181302, 7.64409107])

edited Jul 20 '21 at 08:37

Peter Mortensen

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answered Apr 27 '21 at 16:54

Woodford

3,746
1
15
29

very nice i didn't know about that. thank you – Zaid Khalil Apr 27 '21 at 17:04

score 1 · Answer 5 · edited Jul 20 '21 at 08:38

1

You can use multiple for loops.

list_1 = [2.03898103, 2.23708741, 1.68221573, 1.12352885, 
0.56227805]
list_2 = []

for i in range(0, 4):
     for j in range(0, i):
          list_2[i] += list_1[j]

edited Jul 20 '21 at 08:38

Peter Mortensen

30,738
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answered Apr 27 '21 at 17:02

1

i tried a lot but i did mistakes. now i know my mistake. thx a lot – Zaid Khalil Apr 27 '21 at 17:06
Yeah. Using multiple for loops is often an easy solution to problems that seeam complicated. – Apr 27 '21 at 17:10

Add numbers of lists to the first number of the list

5 Answers5