Sets

Set is unordered mutable collection of unique elements

Set is just like dictionary without values. Sets do not support indexing, slicing, or other sequence-like behavior.

Common uses include membership testing, removing duplicates from a sequence, and computing mathematical operations such as intersection, union, difference, and symmetric difference.

Elements can be only hashable objects - just like keys of dictionary (all immutable objects and instances of classes).

Ways to create a set:

• set()

• {1, 2, 3}

• set([1, 2, 3, 4])

• set("abcdeabcde")

🪄 Code:

some_list = [1, 2, 3, 4]
some_tuple = tuple(some_list)
set_a = set(some_list)
set_b = set(some_tuple)
print(set_a)
print(set_b)

📟 Output:

{1, 2, 3, 4}
{1, 2, 3, 4}

Main methods

🪄 Code:

[method for method in dir({1}) if not method.startswith("__")]

📟 Output:

['add',
 'clear',
 'copy',
 'difference',
 'difference_update',
 'discard',
 'intersection',
 'intersection_update',
 'isdisjoint',
 'issubset',
 'issuperset',
 'pop',
 'remove',
 'symmetric_difference',
 'symmetric_difference_update',
 'union',
 'update']

A lot of different methods for checking various mathematical set properties

Set methods

Method(s)	Description
len()	Return int - length of the set
x in set_a	Return True/False - is object xis part of the set set_a?
set_a | set_b	Return new set - a union (all from both)
set_a & set_b	Return new set - a intersection (common to both)
set_a - set_b	Return new set - a difference (those in set_a that are not in set_b)
set_a < set_b	Return True/False - a issubset (set_a is proper subset of set_b)
set_a > set_b	Return True/False - a issubset (set_b is proper subset of set_a)