Remove Every Nth Element from List in Python

To remove every nth element from a list in Python, the easiest way is to use slicing.

def remove_every_nth(lst, n):
    del lst[n-1::n]
    return lst

example = [1, 2, 3, 4, 5, 6, 7]

print(remove_every_nth(example,3))

#Output:
[1, 2, 4, 5, 7]

When working with collections of data, the ability to easily keep or remove specific items from a collection can be valuable.

One such operation in Python which is common is removing every nth element in a list.

To remove every nth element of a list in Python, utilize the Python del keyword to delete elements from the list and slicing.

For your slice, you want to pass n for the slice step size.

For example, if you have a list and you to remove every 2nd element, you would delete the slice defined by [1::2] as shown below.

lst = [1, 2, 3, 4, 5, 6, 7]

del lst[1::2]

print(lst)

#Output:
[1, 3, 5, 7]

If you want to create a function which will remove every nth element from a list given a list and n, you can use the following:

def remove_every_nth(lst, n):
    del lst[n-1::n]
    return lst

example = [1, 2, 3, 4, 5, 6, 7]

print(remove_every_nth(example,3))

#Output:
[1, 2, 4, 5, 7]

Keeping Every Nth Element in a List in Python

If you want to go the other way and keep every nth element in a list in your Python code, you can also use slicing.

In this case, we will need to adjust the slice we take.

Below is a function which will keep every nth element from a list given a list and n in Python.

def keep_every_nth(lst, n):
    return lst[::n]

example = [1, 2, 3, 4, 5, 6, 7]

print(keep_every_nth(example,3))

#Output:
[1, 4, 7]

Hopefully this article has been useful for you to learn how to remove every nth element from a list in Python.