Please note, this is a STATIC archive of website www.w3resource.com from 19 Jul 2022, cach3.com does not collect or store any user information, there is no "phishing" involved.
w3resource

Python: Insert a specified element in a given list after every nth element

Python List: Exercise - 178 with Solution

Write a Python program to insert a specified element in a given list after every nth element.

Sample Solution:

Python Code:

def inset_element_list(lst, x, n):
    i = n
    while i < len(lst):
        lst.insert(i, x)
        i+= n+1
    return lst

nums = [1, 3, 5, 7, 9, 11,0, 2, 4, 6, 8, 10,8,9,0,4,3,0]
print("Original list:")
print(nums)
x = 20
n = 4
print("\nInsert",x,"in said list after every",n,"th element:")
print(inset_element_list(nums, x, n))

chars = ['s','d','f','j','s','a','j','d','f','d']
print("\nOriginal list:")
print(chars)
x = 'Z'
n = 3
print("\nInsert",x,"in said list after every",n,"th element:")
print(inset_element_list(chars, x, n))

Sample Output:

Original list:
[1, 3, 5, 7, 9, 11, 0, 2, 4, 6, 8, 10, 8, 9, 0, 4, 3, 0]

Insert 20 in said list after every 4 th element:
[1, 3, 5, 7, 20, 9, 11, 0, 2, 20, 4, 6, 8, 10, 20, 8, 9, 0, 4, 20, 3, 0]

Original list:
['s', 'd', 'f', 'j', 's', 'a', 'j', 'd', 'f', 'd']

Insert Z in said list after every 3 th element:
['s', 'd', 'f', 'Z', 'j', 's', 'a', 'Z', 'j', 'd', 'f', 'Z', 'd']

Pictorial Presentation:

Python List: Insert a specified element in a given list after every nth element.

Flowchart:

Flowchart: Insert a specified element in a given list after every nth element.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a Python program to find common elements in a given list of lists.
Next: Write a Python program to create the largest possible number using the elements of a given list of positive integers.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m