Basic cheatsheet for Python mostly based on the book written by Al Sweigart, Automate the Boring Stuff with Python under the Creative Commons license and many other sources.

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From the Python 3 documentation

A set is an unordered collection with no duplicate elements. Basic uses include membership testing and eliminating duplicate entries. Set objects also support mathematical operations like union, intersection, difference, and symmetric difference.

There are two ways to create sets: using curly braces {} and the bult-in function set()

s = {1, 2, 3}
s = set([1, 2, 3])

When creating an empty set, be sure to not use the curly braces {} or you will get an empty dictionary instead.

s = {}
type(s)

A set automatically remove all the duplicate values.

s = {1, 2, 3, 2, 3, 4}
s

And as an unordered data type, they can't be indexed.

s = {1, 2, 3}
s(0)

Using the add() method we can add a single element to the set.

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

And with update(), multiple ones .

s = {1, 2, 3}
s.update([2, 3, 4, 5, 6])
s  # remember, sets automatically remove duplicates

Both methods will remove an element from the set, but remove() will raise a key error if the value doesn't exist.

s = {1, 2, 3}
s.remove(3)
s

s.remove(3)

discard() won't raise any errors.

s = {1, 2, 3}
s.discard(3)
s

s.discard(3)

union() or | will create a new set that contains all the elements from the sets provided.

s1 = {1, 2, 3}
s2 = {3, 4, 5}
s1.union(s2)  # or 's1 | s2'

intersection or & will return a set containing only the elements that are common to all of them.

s1 = {1, 2, 3}
s2 = {2, 3, 4}
s3 = {3, 4, 5}
s1.intersection(s2, s3)  # or 's1 & s2 & s3'

difference or - will return only the elements that are in one of the sets.

s1 = {1, 2, 3}
s2 = {2, 3, 4}
s1.difference(s2)  # or 's1 - s2'

symetric_difference or ^ will return all the elements that are not common between them.

s1 = {1, 2, 3}
s2 = {2, 3, 4}
s1.symmetric_difference(s2)  # or 's1 ^ s2'