Sets

A set is an unordered collection of unique values. Sets shine at two things: removing duplicates and answering "is this in here?" very fast. They also support classic math operations like union and intersection.

What You'll Learn

• Creating sets and removing duplicates
• Adding and removing elements
• Membership testing
• Union, intersection, and difference

Creating Sets

Sets use curly braces, but unlike dictionaries they hold single values, not pairs. Duplicates disappear automatically:

Adding and Removing

Membership Testing

Checking in on a set is very fast, even for huge collections. This is the main reason to reach for a set:

Set Math

A Practical Example

Key Takeaways

• Sets hold unique values with no order: {1, 2, 3}
• set(list) removes duplicates instantly
• add() and discard() change a set
• in on a set is very fast
• | union, & intersection, - difference