Sets

Set is an unordered collection whose values are not indexed and cannot be changed.

Adding and removing items is allowed.
Duplication is not allowed.
Can be of any data type.
Belong to class set.

True and 1 are considered the same value. Same goes for False and 0.

Use len() to get the length of set.

songs = {"Shame", "Walk", "stevie"}
print(len(songs)) # 3

Though you can’t access items using an index, you can use in operator.

print("Walk" in songs) # True
print("Shame" not in songs) # False

We can add and remove items instead of changing items in set.

songs.add("Fake It")
print(songs) # {'Walk', 'stevie', 'Fake It', 'Shame'}

update() adds items from one set to another.

new_songs = {"Good Grief", "Winter Of Our Youth"}
songs.update(new_songs)
print(songs)
"""
{'Shame', 'Walk', 'Good Grief', 'Winter Of Our Youth', 'stevie'}
"""

remove() and discard() lets you remove items from set.

songs.remove("Shame")
songs.discard("Walk")
print(songs) # {'stevie'}

pop() removes a random items from the list.

x = songs.pop()
print(x) # Shame
print(songs) # {'Walk', 'stevie'}

union() or update() joins all items from two sets. You can also use | operator.

songs = {"Shame", "Walk", "stevie"}
new_songs = {"Good Grief", "Send Them Off!", "Us Against the World"}
new = songs.union(new_songs)
print(new)
"""
{'Good Grief', 'Shame', 'Send Them Off!', 'Walk', 'Us Against the World', 'stevie'}
"""

new_new_songs = {"Mountain Sound", "Of The Night", "My Blood"}
new = songs | new_songs | new_new_songs
print(new)
"""
{'Mountain Sound', 'Good Grief', 'Walk', 'Of The Night', 'Shame', 'Us Against the World', 'Send Them Off!', 'My Blood', 'stevie'}
"""

intersection() returns a set with items present in both the sets. You can also use & operator.

ticket = {1, 2, 4, 5, 1}
new_ticket = {2, 45, 6, 1, 4}

new = ticket & new_ticket
print(new) # {1, 2, 4}

difference() returns a set with items in first set not present in other set. You can also use - operator.

new = ticket - new_ticket
old = new_ticket - ticket
print(new) # {5}
print(old) # {45, 6}

symmetric_difference() keeps a set with elements not present in both the sets. You can also use ^ operator.

new = ticket ^ new_ticket
print(new) # {5, 6, 45}