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Sets in Python

Sets in Python 3 are a built-in data type that represent an unordered collection of unique elements. They are defined using curly braces {} or the set() constructor.

Here are some of the main features and uses of sets in Python:

  1. Uniqueness: Sets enforce that all elements they contain are unique, meaning that duplicates are automatically removed.

  2. Membership testing: You can use the in operator to check if an element is in a set, and the not in operator to check if it is not.

  3. Set operations: You can perform common set operations such as union (|), intersection (&), difference (-), and symmetric difference (^) on sets.

  4. Modification: You can add elements to a set using the add() method, and remove elements using the remove() or discard() methods.

  5. Iteration: You can iterate over the elements of a set using a for loop, just like with lists and other iterable objects.

Here's a simple example to demonstrate the basic features of sets in Python (In Python Console):

>>> s = {1, 2, 3}
>>> print(s)
{1, 2, 3}

>>> 2 in s
True

>>> 4 in s
False

>>> s.add(4)
>>> print(s)
{1, 2, 3, 4}

>>> s.remove(4)
>>> print(s)
{1, 2, 3}

>>> for item in s:
...     print(item)
...
1
2
3

Sets are useful for tasks such as removing duplicates from a list, testing for membership, and performing set operations.

Create A Set

we can create a set using {} brackets or using set() constructor

a = {10,"python",23.22,40,True}   # create a set
print(a)      # {True, 40, 10, 'python', 23.22}

a = set([10,"python",23.22,40,True])  # set constructor
print(a)      # {True, 40, 10, 'python', 23.22}

All Set Built In Methods

Method Uses
add() Add an element in the set
clear() Removes all the elements from the set
copy() Create a copy of the set
difference() find difference between two or more sets and return new set
difference_update() Removes the common elements in specified set and add in existing
discard() Remove the specified item
intersection() Return intersection of two other sets
intersection_update() Removes all elements except common with specified set(s)
isdisjoint() Returns True if two sets have a intersection else False
issubset() Returns True if another set contains this set else False
issuperset() Returns True if set contains another set else False
pop() Removes random element from the set and return
remove() Removes the specified element from the set or raise error
symmetric_difference() Returns a set with the symmetric differences of two sets except common items
symmetric_difference_update() remove elements from a set if present or insert with specified set
union() Return a set containing the union of sets
update() Update the set with the union of this sets

Sets methods Examples in Python

Set Add() Method

add() method add new element in set

a = {True, 40, 10, 'python', 23.22}
a.add(88)
print(a)      # {True, 40, 10, 23.22, 88, 'python'}

Set Pop() Method

pop() method Remove a random element from a set and return

a = { 40, 10, 'python', 23.22}
r = a.pop()
print(r)      # 40

Set Clear() Method

remove all element from sets .

a = {True, 40, 10, 'python', 23.22}
a.clear()
print(a)      # set()

Set Difference() Method

return the difference of two sets as new set . remove common elements.

a = {True, 40, 10, 'python', 23.22}
b = {10,20,435,"python"}
print(a.difference(b))      # {40, True, 23.22}

Set Difference_update() Method

remove duplicate item from two sets with specified set. it does not return new set.

a = {True, 40, 10, 'python', 23.22}
b = {10,20,435,"python"}
a.difference_update(b)
print(a)      # {True, 40, 23.22}

Set Intersection() Method

intersection() method return the intersection of two sets. intersection_update() method modify existing set it does not return new .

a = {True, 40, 10, 'python', 23.22}
b = {10,20,435,"python"}
print(a.intersection(b))      # {'python', 10}

Set Isdisjoint() Method

Return True if a sets is disjoint with specified set.

a = {True, 40, 10, 'python', 23.22}
b = {10,20,435,"python"}
print(a.isdisjoint(b))      # False

Set Union() Method

return the union of a set with specified set(All items). duplicate value excluded.

a = {True, 40, 10, 'python', 23.22}
b = {10,20,435,"python"}
print(a.union(b))      # {True, 40, 10, 'python', 435, 20, 23.22}