Set add() Method in Python
The Python set add() method adds a given element to a set if the element is not present in the set in Python.
Example: Add Element to an Empty set
It is used to add a new element to the empty set.
GEEK = set()
GEEK.add('s')
print("Letters are:", GEEK)
# adding 'e' again
GEEK.add('e')
print("Letters are:", GEEK)
# adding 's' again
GEEK.add('s')
print("Letters are:", GEEK)
Output
Letters are: {'s'}
Letters are: {'e', 's'}
Letters are: {'e', 's'}
Set add() Syntax
Syntax: set.add( elem )
Parameters
- elem: The element that needs to be added to a set.
Return
The add() method does not return anything
What is set add() Method
In Python, a set is an unordered collection of unique elements. The add() method is a built-in method in Python that is used to add a single element to a set. If the element is already present in the set, the set remains unchanged.
Python Set add() Method Examples
Before going to the example we are assuming the time complexity of the set.add() function is O(1) because the set is implemented using a hash table.
Now let’s look at some use cases of add() function in Python with examples:
- Add Element to an Empty set
- Add a new element to a Python set
- Add an element in a set that already exists
- Adding any iterable to a set
1. Add Element to an Empty set
It is used to add a new element to the empty set.
GEEK = set()
GEEK.add('s')
print("Letters are:", GEEK)
# adding 'e' again
GEEK.add('e')
print("Letters are:", GEEK)
# adding 's' again
GEEK.add('s')
print("Letters are:", GEEK)
Output
Letters are: {'s'}
Letters are: {'e', 's'}
Letters are: {'e', 's'}
2. Add a new element to a Python set
It is used to add a new element to the set if it is not existing in a set.
# set of letters
GEEK = {'g', 'e', 'k'}
# adding 's'
GEEK.add('s')
print("Letters are:", GEEK)
# adding 's' again
GEEK.add('s')
print("Letters are:", GEEK)
Output:
Letters are: {'e', 's', 'g', 'k'}
Letters are: {'e', 's', 'g', 'k'}
3. Add element in a set that already exists
It is used to add an existing element to the set if it is existing in the Python set and check if it gets added or not.
# set of letters
GEEK = {6, 0, 4}
# adding 1
GEEK.add(1)
print('Letters are:', GEEK)
# adding 0
GEEK.add(0)
print('Letters are:', GEEK)
Output:
Letters are: {0, 1, 4, 6}
Letters are: {0, 1, 4, 6}
4. Adding any iterable to a set
We can add any Python iterable to a set using Python add or Python update function, if we try to add a list using the add function we get an unhashable Type error.
# Python code to demonstrate addition of tuple to a set.
s = {'g', 'e', 'e', 'k', 's'}
t = ('f', 'o')
l = ['a', 'e']
# adding tuple t to set s.
s.add(t)
# adding list l to set s.
s.update(l)
print(s)
Output :
{'a', 'g', 'k', 'e', ('f', 'o'), 's'}In this article we covered the add() function in Python. Set add() method in Python is useful to avoid entry of duplicate item in the set.
Read More on Set Methods
Set add() Method in Python – FAQs
How to Use the add() Method with Sets in Python?
The
add()method in Python is used to add a single element to a set. If the element is already present, it does nothing as sets do not allow duplicate elements.Example:
# Creating a set
my_set = {1, 2, 3}
# Adding a new element to the set
my_set.add(4)
print(my_set) # Output: {1, 2, 3, 4}
# Adding an existing element to the set
my_set.add(3)
print(my_set) # Output: {1, 2, 3, 4} (no change since 3 is already in the set)
How to Add Elements to a Set in Python?
You can add elements to a set using the
add()method for single elements or theupdate()method for multiple elements.Using
add()Method:my_set = {1, 2, 3}
my_set.add(4)
print(my_set) # Output: {1, 2, 3, 4}Using
update()Method:my_set = {1, 2, 3}
my_set.update([4, 5, 6])
print(my_set) # Output: {1, 2, 3, 4, 5, 6}
What is the Difference Between add() and update() in Sets?
my_set = {1, 2, 3}
my_set.add(4)
print(my_set) # Output: {1, 2, 3, 4}
add()Method: Adds a single element to the set. If the element already exists, it does nothing.
update()Method: Adds multiple elements to the set. It can take any iterable as an argument (e.g., lists, tuples, sets).my_set = {1, 2, 3}
my_set.update([4, 5, 6])
print(my_set) # Output: {1, 2, 3, 4, 5, 6}
What Happens When an Existing Item is Added to a Set in Python?
When an existing item is added to a set using the
add()method, nothing changes. Sets automatically handle duplicates by ignoring any element that is already present.Example:
my_set = {1, 2, 3}
my_set.add(3)
print(my_set) # Output: {1, 2, 3} (no change since 3 is already in the set)
Are Sets Ordered in Python?
No, sets are unordered collections in Python. This means that the items have no defined order, and you cannot rely on the order of elements when you iterate over a set or print it.
Example:
my_set = {3, 1, 2}
print(my_set) # Output: {1, 2, 3} or any other permutation (the order is not guaranteed)
