Data Structures

In the previous chapters we have talked about primitive data types, such as int, float, bool, str, and None. These are the basic building blocks of any program, but they are not enough to solve most real-world problems. In this chapter we will introduce more complex data types, which are called data structures.

We will cover the following data structures:

• Lists
• Tuples
• Sets
• Dictionaries
• Dataclasses
• Enumerations

Guidance

If you don't know which type of collection to use, here is a simple decision diagram:

flowchart TD
    A[I want to save a list of things]

    A --> B{{ Do my values have a unique key<br/> and associated value? }}
    B -->|No| D{{Do I mainly check if a value is the collection?}}

    D -->|Yes| E{{Are all values unique?}}
    D -->|No| I
    
    E -->|No| I{{Do I only insert values once?}}
    I -->|Yes| J[use <code>tuple</code>]
    I -->|No| C[use <code>list</code>]
    B -->|Yes| L[use <code>dict</code>]
    
    E -->|Yes| M{{Do I need to know the order of the values?}}
    M -->|Yes| C
    M -->|No| G{{Do I only insert values once<br/>and then check against those?}}
    G -->|Yes| H[use <code>frozenset</code>]
    G -->|No| F[use <code>set</code>]