Python | Pair summation of list elements

Sometimes, while working with Python list, one can have a problem in which one needs to find perform the summation of list in pair form. This is useful as a subproblem solution of bigger problem in web development and day-day programming. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using loop
This is the brute force method to perform this particular task. In this, we just iterate the list till last element in skipped manner to get all the pair sums in other list in an iterative way.

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate working of
# Pair summation of list
# Using loop
  
# initializing list
test_list = [4, 5, 8, 9, 10, 17]
  
# printing list
print("The original list : " + str(test_list))
  
# Pair summation of list
# Using loop
res = []
for ele in range(0, len(test_list), 2):
    res.append(test_list[ele] + test_list[ele + 1])
  
# Printing result
print("Pair summation of list : " + str(res))

chevron_right


Output :



 
The original list : [4, 5, 8, 9, 10, 17]
Pair summation of list : [9, 17, 27]

 

Method #2 : Using zip() + list comprehension
This task can also be performed using the combination of above functionalities. In this, we just iterate the list and the task of combining pairs is performed by zip(). Works only on Python2.

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python code to demonstrate working of
# Pair summation of list
# zip() + list comprehension
  
# initializing list
test_list = [4, 5, 8, 9, 10, 17]
  
# printing list
print("The original list : " + str(test_list))
  
# Pair summation of list
# zip() + list comprehension
res = [i + j for i, j in zip(test_list, test_list[1:])[::2]]
  
# Printing result
print("Pair summation of list : " + str(res))

chevron_right


Output :

 
The original list : [4, 5, 8, 9, 10, 17]
Pair summation of list : [9, 17, 27]


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :

Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.