Master Python List Deletion: remove, pop, and del Explained

Introduction

In Python, there are three common ways to delete elements from a list: remove, pop, and del.

1. remove

Deletes a single element by value, removing the first occurrence that matches.

>> str = [1, 2, 3, 4, 5, 2, 6]
>>> str.remove(2)
>>> str
[1, 3, 4, 5, 2, 6]

2. pop

Deletes an element by index and returns the removed element. It can also be used on any indexable object.

>> str = [0, 1, 2, 3, 4, 5, 6]
>>> str.pop(1)  # pop returns the removed element
>>> str
[0, 2, 3, 4, 5, 6]

>>> str2 = ['abc', 'bcd', 'dce']
>>> str2.pop(2)
'dce'
>>> str2
['abc', 'bcd']

3. del

Deletes elements based on their index. It can remove a single element, a slice, or an entire object.

>> str = [1, 2, 3, 4, 5, 2, 6]
>>> del str[1]
>>> str
[1, 3, 4, 5, 2, 6]

>>> str2 = ['abc', 'bcd', 'dce']
>>> del str2[1]
>>> str2
['abc', 'dce']

>>> # Delete a range (slice)
>>> str = [0, 1, 2, 3, 4, 5, 6]
>>> del str[2:4]  # removes elements at index 2 up to but not including 4
>>> str
[0, 1, 4, 5, 6]

>>> # Delete the entire list object
>>> str = [0, 1, 2, 3, 4, 5, 6]
>>> del str
>>> str
NameError: name 'str' is not defined

Note: del removes the reference (variable) to an object, not the object itself; the actual data is reclaimed by Python's garbage collector.

Alternative Approach

A different way to “delete” elements is to build a new collection that excludes unwanted items.

s1 = (1, 2, 3, 4, 5, 6)
s2 = (2, 3, 5)
s3 = []
for i in s1:
    if i not in s2:
        s3.append(i)
print('s1_1:', s1)
s1 = s3
print('s2:', s2)
print('s3:', s3)
print('s1_2:', s1)