i'm using Python and I have the following list A = [10,20,30,40] how can obtain a new list such as I'm adding the second element to the first, the third to the second and fourth to the third. Meaning the output would be [30,50,70].

CodePudding user response：

Can use simple list comprehension like this:

a = [10,20,30,40]
b = [a[i]   a[i 1] for i in range(len(a)-1)]

b
[30, 50, 70]

CodePudding user response：

Take a look at the pairwise recipe from the itertools module (which will be added as a function of itertools in 3.10). Once you've copied that, you can just do:

[x   y for x, y in pairwise(A)]

or for fun with less custom code, add imports from operator import add and from itertools import starmap and you can make an iterator that produces the results lazily with:

starmap(add, pairwise(A))  # Wrap in list if you need a list

CodePudding user response：

a = [10,20,30,40,50]
new_list = []
for i in range(1, len(a)):
    new_list.append(a[i]   a[i-1])