Sets

When we hear the word "set," we often think about sets in mathematics — a collection of distinct, well-defined elements. Python adopts the same concept, but as a built-in data type and data structure.

If you're not familiar with how Python sets work, don’t worry — I'll explain it clearly.

What is a Set in Python?

A set in Python is an unordered collection of well-defined, unique, and hashable objects. Sets are defined using curly braces {}, and elements inside are separated by commas.

 a = {1, 2, 3, 4}

🔑 Key Properties of Python Sets:

Unique Elements
Sets automatically remove duplicates — every element is stored only once.
Unordered
Unlike lists and tuples, sets have no index — elements do not have a fixed position.
Hashable Elements Only
Sets only allow hashable (i.e., immutable) items like numbers, strings, or tuples. You can't add mutable types like lists or dictionaries to a set.
Mutable Container
While the elements must be hashable, the set itself is mutable — you can add or remove elements any time using methods like .add() or .remove().

How to Convert another hash sequence datatype in sets ?

to do that we use function set( ).

Set only store immutable datatypes

hash

hash is a fixed sized number that is calculated from data.

hashable

hashable means an object that have hash value , immutable.

unhashable

hashable means an object that do not have hash value , mutable.

benefits of hashable element

A set can only store elements that are hashable.
When you add an element to a set, Python calculates its hash value and stores it based on that value.

When you want to check if an element is present in a set (a membership test), Python uses the hash value to jump directly to the location where that element would be — making the lookup very fast.

how its internally work you can understand using image given bellow.

In contrast, a list checks each element one by one during a membership test, which is much slower for large datasets.

when we use sets

when we want to check membership because that operation is very fast on set compared to list, tuple or etc.
when we want a sequence whose elements are unique.
when we want to perform set operation on a sequence.

Python Set Methods

1. add( )

add a given no to a set.

2. remove( )

remove given element from set.

3. clear( )

delete all elements of set and return an empty set.

4. del

delete the set and when we call set raise error and say not defined.

5 . pop( )

return and remove random element from set.

set operations

for understanding some method we have to same knowledge about sets operation and also along with this we cover how this operation is done using python sets method