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How to Remove the Last N Elements of a List in Python

Oct 5, 2020 1 min read

Removing the last N elements of a list can be tricky at times.

Suppose I have the following list.

lst = [1, 2, 3, 4]

Creating a shallow copy

Most of us know that we can use -1 to get the last element of a list. Similar, we can use the slice notation along with negative index to remove the last element.

print(lst[-1])  # 4
print(lst[:-1]) # [1, 2, 3]
print(lst)      # [1, 2, 3, 4]

Note that this will create a shallow copy of the list. We can remove the last N element of a list like so:

lst = lst[:-n]

But, this actually does not work when n == 0 because it results in this operation, which will grab nothing from the list.

print(lst[:-0]) # []

We can circumvent this by slicing with -n or None, which will evaluate to -n when n > 0 and None when n == 0.

lst = lst[:-n or None]

Modifying the original list

If we don’t want to reassign the list, we can directly modify the original list with del.

del lst[-1:]
print(lst]) # [1, 2, 3]

To remove the last N elements in a list, we can do the following:

del lst[-n:]