Python | Add element at alternate position in list

Sometimes, while working with Python list, we can have a problem in which we need to add elements in list alternatively i.e at even positions and reorder the list accordingly. This has a potential application in many domains such as day-day programming and competitive programming. Let’s discuss certain way in which this problem can be solved.

Method : Using join() + list()
This method can be used to solve this problem in one line. In this, we just join all the elements alternatively with target element and then convert back to list using list().

# Python3 code to demonstrate working of 
# Add element at alternate position in list 
# using join() + list() 
  
# initialize list 
test_list = ['a', 'b', 'c', 'd', 'e', 'f'] 
  
# printing original list 
print("The original list is : " + str(test_list)) 
  
# initialize ele  
ele = '#'
  
# Add element at alternate position in list 
# using join() + list() 
res = list(ele.join(test_list)) 
  
# printing result 
print("List after alternate addition : " + str(res)) 

Output :

The original list is : ['a', 'b', 'c', 'd', 'e', 'f']
List after alternate addition : ['a', '#', 'b', '#', 'c', '#', 'd', '#', 'e', '#', 'f']

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