1. Python
  2. Python | Insert a value after every k letters in a given list of strings

Python | Insert a value after every k letters in a given list of strings

As we know, inserting an item into a list is quite common, but sometimes we need to work with a list of strings, looking at each letter and inserting some repetitive items at a fixed frequency. Let`s see how to solve this problem with Python.

Method # 1: Using the enumerate () method

# Python program to insert value after
# every k letters in the given list of strings

list1 = [ ` p` , `y` , ` t` , `h` , ` o` , `n` ] 

 
# print original list

print   ( "Original list:" + str (list1)) 

 
# initialization to

k = ` G`

 
# initialization N

N = 2

 
# using join () + enumerate ()
# insert K after every Nth number

output = list (`` .join (i + k * < code class = "plain"> (N % 2 = = 1 ) 

for N, i in enumerate (list1))) 

 
# print result

print ( "The lists after insertion:" + str (output)) 

Output: 

 Original list: [`p`,` y`, `t`,` h`, `o`,` n`] The lists after insertion: [`p`,` y`, `G`,` t`, `h`,` G`, `o`,` n`, `G`]

Method # 2: Used no itertools

# Python program to insert value after
# every k letters in the given list lines

from itertools import chain 

 

list1 = [ `p` , ` y` , `t` , `h` , `o` , ` n` ] 

 
# print the original list

print ( "Original list:" + str (list1)) 

 
# initialize to

k = `x`

 
# initialization N

N = 3

 

 
# insert K after every Nth number

output = list (chain ( * [list1 [i: i + N] + [k] 

if len (list1 [i: i + N]) = = N  else list1 [i: i + N] 

  for i in range ( 0 , len (list1), N)])) 

 
# print result

print ( "The lists after insertion:" + str (output)) 

Exit:

 Original list: [`p`,` y`, `t`,` h`, `o`,` n`] The lists after insertion: [`p`,` y`, `t`,` x`, `h` , `o`,` n`, `x`]