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Python Set

A Set is an unordered collection data type that is iterable, mutable, and has no duplicate elements.

Python's set class represents the mathematical notion of a set. The major advantage of using a set, as opposed to a list, is that it has a highly optimized method for checking whether a specific element is contained in the set. This is based on a data structure known as a hash table.

A set is a collection which is unordered and unindexed. In Python sets are written with curly brackets.

In a set we can't have duplicate items.

Creating set

In Python sets are written with curly brackets.

Accessing values in set

As set is unindexed we can't use [] to access elements of a set.

But we can use for loop to access set elements:

Updating set

You can add to elements in a set with the add() method:

Delete set Elements

Set elements can be removed using pop() and remove() methods:

  • pop() method delete element from begining of set
  • remove() method takes an argument and delete that element from set

Python Built-in set Functions

Function Description
len(set) Gives the total length of the set (duplicate values excluded).
max(set) Returns item from the set with max value.
min(set) Returns item from the set with min value.
set(seq) Converts a tuple or list into set.

Python Built-in set Methods

Method Description
set.add(x) Adds the item x to set if it is not already present in the set
set.clear() Empties the whole set
set.copy(o) Copy a set to another set
set.union(s) Returns a union of two set. Using the | operator between 2 sets is the same as writing set1.union(set2)
set.intersection(s) Returns intersections/common of two sets.The & operator comes can also be used in this case.
set.difference(s) Returns a set containing all the elements of invoking set but not of the second set
set.pop() Remove element from begining
set.remove(elem) Remove elem from set