The set.add() method in Python adds a single element to a set. It automatically ignores duplicate values and only accepts immutable (hashable) types like numbers, strings and tuples. Mutable types such as lists or dictionaries cannot be added.

Example: In this example, an empty set is created using set() function then an element 's' is added in the empty set 'a' using add() function.

a = set()
a.add('s')
print(a)

{'s'}

Explanation: set() creates an empty set and a.add('s') adds 's' to the set

Syntax

set_name.add(element)

• Parameter: element - The value to be added to the set.
• Returns: It does not return anything (None).

Examples

Example 1: In this example, we add elements to a set of characters and observe that duplicate values are ignored.

a = {'g', 'e', 'k'}

a.add('s')
print(a)

a.add('s')
print(a)

{'g', 'k', 's', 'e'}
{'g', 'k', 's', 'e'}

Explanation: a.add('s') adds 's' to the set and calling a.add('s') again does not change the set.

Example 2: In this example, we add numbers to a set and see how duplicate values are handled.

a = {6, 0, 4}

a.add(1)
print(a)

a.add(0)
print(a)

{0, 1, 4, 6}
{0, 1, 4, 6}

Explanation: a.add(1) inserts 1 into the set and a.add(0) does not change the set because 0 already exists.

Example 3: Here, we add a tuple using add() and multiple elements from a list using update().

s = {'g', 'e', 'e', 'k', 's'}
t = ('f', 'o')
l = ['a', 'e']

s.add(t)
s.update(l)
print(s)

{'k', 's', ('f', 'o'), 'g', 'e', 'a'}

Explanation:

• Duplicate 'e' is removed when creating the set and s.add(t) adds the tuple ('f', 'o') as a single element
• s.update(l) adds elements of list l individually and duplicate 'e' from l is ignored.

Related Articles:

Set Methods