Remove items from Set - Python

We are given a set and our task is to remove specific items from the given set. For example, if we have a = {1, 2, 3, 4, 5} and need to remove 3, the resultant set should be {1, 2, 4, 5}.

Using remove()

remove() method in Python is used to remove a specific item from a set. If the item is not present it raises a KeyError so it's important to ensure item exists before using it.

a = {1, 2, 3, 4, 5}
a.remove(3)  
print(a) 

{1, 2, 4, 5}

Explanation:

• a.remove(3) removes element "3" from the set a and if element is not found then it raises a KeyError.
• after removal of element, set a is printed and element "3" is no longer part of the set.

Using discard()

discard() method in Python removes a specified element from a set without raising a KeyError even if element does not exist in set. It's a safer alternative to remove() as it doesn't cause an error when element is missing.

a = {1, 2, 3, 4, 5}
a.discard(3)
a.discard(6)  
print(a)  

{1, 2, 4, 5}

Explanation:

• discard(3) method removes element "3" from the set a if it exists.
• discard(6) method does nothing because "6" is not present in set and no error is raised.

Using pop()

pop() method removes and returns a random element from a set. Since sets are unordered element removed is arbitrary and may not be predictable.

a = {1, 2, 3, 4, 5}
r = a.pop()
print(f"Removed: {r}")
print(a)  

Removed: 1
{2, 3, 4, 5}

Explanation:

• pop() method removes and returns a random element from the set "a" and removed element is stored in variable "r".
• After removal, set "a" is printed showing remaining elements without randomly chosen item.

Using clear()

clear() method removes all elements from a set effectively making it an empty set. It does not return any value and directly modifies original set.

a = {1, 2, 3, 4, 5}
a.clear()  
print(a) 

set()

Explanation: clear() method removes all elements from the set "a", leaving it empty.

Also read: remove(), discard(), clear(), pop(), set.