Python | Sum two unequal length lists in cyclic manner

Last Updated : 05 Mar, 2019

Given two unequal length lists, the task is to add elements of two list such that when elements of smaller list are over, add elements in a circular manner till all element of the larger list is iterated.

Let’s discuss different ways we can do this task.

Method #1 : Using Iteratools and zip

# Python code to add two different
# length lists in cyclic manner
  
# Importing
from itertools import cycle
  
# List initialization
list1 = [150, 177, 454, 126]
list2 = [9, 44, 2, 168, 66, 80, 123, 6, 180, 184]
  
# Using zip
output = [x + y for x, y in zip(cycle(list1), list2)]
  
# Printing output
print(output)

Output:

[159, 221, 456, 294, 216, 257, 577, 132, 330, 361]

Method #2 : Using Iteratools and starmap

# Python code to add two different 
# length lists in cyclic manner
  
# Importing
from itertools import starmap, cycle
from operator import add
  
# List initialization
list1 = [150, 177, 454, 126]
list2 = [9, 44, 2, 168, 66, 80, 123, 6, 180, 184]
  
# Using starmap
output = list(starmap(add, zip(cycle(list1), list2)))
  
# Print output
print(output)

Output:

[159, 221, 456, 294, 216, 257, 577, 132, 330, 361]

Method #3 : Using List comprehension

# Python code to add two different
# length lists in cyclic manner
  
# List initialization
list1 = [150, 177, 454, 126]
list2 = [9, 44, 2, 168, 66, 80, 123, 6, 180, 184]
  
# List comprehension
output = [list1[i % len(list1)]+list2[i]
             for i in range(len(list2))]
  
# Printing output
print(output)

Output:

[159, 221, 456, 294, 216, 257, 577, 132, 330, 361]

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