I got two lists:
list_1 = [a1, a2, a3, ... a36]
list_2 = [b1, b2, b3,... b12]
how can i get the sum of this two lists, according to an algorithm such as
a1 + b1, a1+b2, a1+b3,... , a1+b12
then
a2+b1, a2+b2, a2+b3,..., a2+b12
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This is unclear. Do you need just the first two iterations of this pattern? What output do you require: two lists or a list of lists? Can you provide a minimal reproducible example?jpp– jpp2018-11-07 10:53:55 +00:00Commented Nov 7, 2018 at 10:53
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Possible duplicate of Matrix Multiplication in python?Egalth– Egalth2018-11-07 10:54:42 +00:00Commented Nov 7, 2018 at 10:54
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3 Answers
Use itertools.product
Ex:
from itertools import product
list_1 = [1,2,3]
list_2 = [4,5,6]
print([sum(i) for i in product(list_1, list_2)])
Output:
[5, 6, 7, 6, 7, 8, 7, 8, 9]
1 Comment
Romeo Kienzler
that's the solution I even prefer over mine :) Only drawback is the need for an import and it's maybe not obvious to everyone what "product" does - but among all proposed solutions this is the most sound to me, kudos!
This simple code would work too:
list_1 = [1, 2, 3, 4]
list_2 = [5, 6, 7]
list_3 = [a+b for a in list_1 for b in list_2] # Adding them up pairwise
Now, list_3 would contain all the sums.
1 Comment
Romeo Kienzler
that's the solution I even prefer over mine :) Especially since it doesn't need external imports
From your question you seem to want this:
list_1 = [1,2,3]
list_2 = [4,5,6]
list_2_sum = sum(list_2)
[i + list_2_sum for i in list_1]
#[16, 17, 18]
Or if you list_1 is longer:
list_1 = [1, 2, 3, 4]
list_2 = [4, 5, 6]
list_2_sum = sum(list_2)
[x + list_2_sum for x, _ in zip(list_1, list_2)]
#[16, 17, 18]
