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Sets in Python

Hello, Python enthusiasts! Today, we’re diving deep into the world of sets in Python. Sets are a remarkable data structure that offer unique properties and operations. So, join me, DataSagar, as we unravel the mysteries of sets and understand their power.

Understanding Sets

In Python, sets are a type of collection, similar to lists and tuples. However, they come with their own distinct characteristics. Unlike lists and tuples, sets are unordered, which means they don’t preserve the order of elements. Moreover, sets only store unique elements, ensuring that each item appears only once within a set.

To create a set, you use curly braces {}. Inside these braces, you place the elements you want to include in the set, separated by commas. Here’s a simple example:

my_set = {1, 2, 3, 4, 5}

In this example, my_set is a set containing the integers from 1 to 5. Notice how there are no duplicate elements, even if you include them initially.

Converting Lists to Sets

Sometimes, you may want to convert a list into a set. This can be easily accomplished using the set() function, a process known as type casting. When you pass a list as an argument to set(), it transforms the list into a set and removes any duplicates.

my_list = [1, 2, 2, 3, 4, 4, 5]
my_set = set(my_list)  # Converts the list to a set

Now, my_set will contain unique elements, removing any duplicate values present in the original list.

Basic Set Operations

Sets come with several useful operations that allow you to manipulate their contents. Let’s explore some of these fundamental operations:

Adding Elements

You can add elements to a set using the add() method. This method takes an argument, the element you want to add to the set.

my_set = {1, 2, 3}
my_set.add(4)  # Adds the element 4 to the set

Removing Elements

Removing elements from a set is accomplished with the remove() method. Similar to add(), you provide the element you wish to remove as the argument.

my_set = {1, 2, 3, 4}
my_set.remove(3)  # Removes the element 3 from the set

Checking for Existence

To verify if an element exists in a set, use the in keyword. It returns True if the item is present in the set and False otherwise.

my_set = {1, 2, 3}
if 2 in my_set:
    print("2 is in the set")  # This will be printed

Set Operations

Sets support various mathematical operations that can be used to manipulate them. Let’s explore two essential operations: intersection and union.


The intersection of two sets is a new set that contains only the elements present in both sets. In Python, you can find the intersection of two sets using the & operator.

set_A = {1, 2, 3, 4}
set_B = {3, 4, 5, 6}
intersection_result = set_A & set_B  # Finds the intersection

intersection_result will contain {3, 4} because those are the elements present in both set_A and set_B.


The union of two sets creates a new set that contains all the elements from both sets. In Python, you can find the union of two sets using the | operator.

set_C = {1, 2, 3}
set_D = {3, 4, 5}
union_result = set_C | set_D  # Finds the union

union_result will contain {1, 2, 3, 4, 5} because it combines all the elements from both set_C and set_D.

Subset Check

You can check if one set is a subset of another using the issubset() method. This method returns True if the first set is a subset of the second set and False otherwise.

set_E = {1, 2}
set_F = {1, 2, 3, 4}
is_subset = set_E.issubset(set_F)  # Checks if set_E is a subset of set_F

In this case, is_subset will be True because all the elements in set_E are present in set_F.

Sets in Python are a versatile and powerful data structure that offer unique capabilities for handling collections of data. Whether you need to perform set operations, check for element existence, or manipulate data without duplicates, sets are your reliable ally.

In this article, we’ve explored the fundamentals of sets, including their creation, basic operations, and mathematical set operations. Armed with this knowledge, you can harness the full potential of sets in your Python programming journey.

Keep experimenting, practicing, and stay tuned for more exciting content from

Happy coding!

The author of this blog post is a technology fellow, an IT entrepreneur, and Educator in Kathmandu Nepal. With his keen interest in Data Science and Business Intelligence, he writes on random topics occasionally in the DataSagar blog.
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