Job Ready Python

Lesson 11Diving Deeper into Data Structures: Sets

We've seen how to use lists, tuples, and dictionaries to store data. In this lesson, we tackle one final basic data structure: sets. A set is an unordered collection of items in which every set element is unique and must be immutable (cannot be changed). A set itself, however, is mutable. We can add or remove items from it.

LEARNING OBJECTIVES

By the end of this lesson, you will be able to:

• Store, retrieve, and manipulate data in a set.
• Iterate through a set.
• Determine if values exist in a set.
• Clear or remove items from a set.
• Work with multiple sets to determine differences including intersections and unions.

SETS

As mentioned, a set is an unordered and unindexed collection of unique items. Specifically:

• The values stored in a set are not indexed in any way. To retrieve an item from a set, you use the value itself, rather than an index.
• Each item in a set must be unique. You cannot include multiple items with the same value in the same set.
• The contents of a set are not ordered. You can add the items in any order you wish, and Python will typically retrieve them in a different, random order.

The steps to create a set are similar to those used to create other data collections, such as lists and tuples. The main difference is the use of curly braces ({}) to define the collection as a set.

It is important that we differentiate dictionaries from sets. Dictionaries and sets are almost identical, except that sets do ...