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Add and Remove Items from Set

Zero-dependency Python snippets for adding and removing items from sets using the standard library.

6 snippets available in this sub-category.

Simple

Add item to set

set add insert data-structures

Add a single item to a set

fruits = {"apple", "banana"}
fruits.add("cherry")
print(fruits)  # {'apple', 'banana', 'cherry'}

Notes

  • add() inserts an item if not present
  • No error if item already exists

Remove item from set

set remove delete data-structures

Remove an item from a set

fruits = {"apple", "banana", "cherry"}
fruits.remove("banana")
print(fruits)  # {'apple', 'cherry'}

# KeyError if item not present
# fruits.remove('orange')  # Raises KeyError

Notes

  • remove() raises KeyError if item not found

Discard item from set

set discard safe data-structures

Discard an item from a set (no error if missing)

fruits = {"apple", "banana"}
fruits.discard("banana")
fruits.discard("orange")  # No error if not present
print(fruits)  # {'apple'}

Notes

  • discard() does not raise error if item is missing

Pop item from set

set pop remove data-structures

Remove and return an arbitrary item from set

fruits = {"apple", "banana", "cherry"}
item = fruits.pop()
print(item)  # Random item
print(fruits)  # Remaining items

Notes

  • pop() removes and returns a random element
  • Raises KeyError if set is empty

Complex

Update set with multiple items

set update add multiple data-structures

Add multiple items to a set

numbers = {1, 2}
numbers.update([2, 3, 4])
print(numbers)  # {1, 2, 3, 4}

# Update with another set
numbers.update({5, 6})
print(numbers)  # {1, 2, 3, 4, 5, 6}

Notes

  • update() adds all elements from iterable(s)
  • Duplicates are ignored

Remove multiple items from set

set remove difference_update subtract data-structures

Remove multiple items from a set

numbers = {1, 2, 3, 4, 5}
numbers.difference_update([2, 3])
print(numbers)  # {1, 4, 5}

# Remove using set subtraction
numbers = {1, 2, 3, 4, 5}
numbers -= {4, 5}
print(numbers)  # {1, 2, 3}

Notes

  • difference_update() removes all elements found in the argument
  • Subtraction operator -= can also be used

🔗 Cross Reference

🏷️ Tags

set, add, remove, discard, pop, update, difference_update, data-structures

📝 Notes

  • Use add(), remove(), discard(), pop(), update(), and difference_update() for set mutation
  • discard() is safer than remove() for unknown items