Set

It is a collection of unordered items. each element in the set must be unique, immutable and the set removes the duplicate elements.

Creating a Set:

The set can be created by enclosing the comma-separated immutable items with the curly braces {}. 

Python also provides the set() method, which can be used to create the set by the passed sequence.

day={1,2,3,4,5,6}

Creating empty set:

s={}, it creates empty dictionary.

s=set()

Add item to the list:

Add(): It is used to add a single item to the set.

day={1,2,3,4,5,6}

day.add(9)

day 

Update(): It is used to add multiple item to set.

Remove item from the list:  Remove() and Discard()

Remove(): It will throw an error if the item doesn't exist.

day={1,2,3,4,5,6}

day.remove(9)

day

Discard(): It will not throw an error if the item doesn't exist.

day={1,2,3,4,5,6}

day.discard(9)

day

Set Operation:

• union

s1={1,2,3,4,5,6}

s2={3,4,5,6,7,9,10}

s=s1.union(s2)

s

print(s1|s2)

• Intersection

s1={1,2,3,4,5,6}

s2={3,4,5,6,7,9,10}

s=s1.intersection(s2)

s

print(s1&s2)

• Difference

print(s1-s2)

print(s1.difference(s2))

The intersection_update() method removes the items from the original set that are not present in both the sets.

s1={1,2,3,4,5,6}

s2={3,4,5,6,7,9,10}

s3={1,2,6,7}

s1.intersection_update(s2,s3)

print(s1,s2)

• Symmetric difference: Present in one set or the other but not in both sets.

1.

s1={1,2,3,4,5,6}

s2={3,4,5,6,7,9,10}

print(s1^s2)

2.

s1={1,2,3,4,5,6}

s2={3,4,5,6,7,9,10}

print(s1.symmetric_difference(s2))

Set Comparison

Equal Operator: checks if two sets have the same elements, regardless of their order.

a={4,5}

b={4,5,6,7,8}

print(a==b)

Not Equal Operator: checks if two sets are not equal.

a={4,5}

b={4,5,6,7,8}

print(a!=b)

< : checks if the left set is a proper subset of the right set

a={4,5}

b={4,5,6,7,8}

print(a<b)

<=: checks if the left set is a subset of the right set.

a={4,5}

b={4,5,6,7,8}

print(a<=b)

>:checks if the left set is a proper superset of the right set.

a={4,5}

b={4,5,6,7,8}

print(a>b)

>=: checks if the left set is a superset of the right set

a={4,5}

b={4,5,6,7,8}

print(a>=b) 

Frozen Sets: It is an immutable version of the built. It is similar to a set, but its contents cannot be changed once a frozen set is created.

Frozen set objects can be used as elements of other sets or dictionary keys, while standard sets cannot.

We can use a frozen set as a key in dictionaries or as an element of another set.

fs=frozenset([1,2,3,4,5,6])

fs

fs.add(9)