Chapter 3. Data Types and Structures

Bad programmers worry about the code. Good programmers worry about data structures and their relationships.

Linus Torvalds

This chapter introduces the basic data types and data structures of Python, and is organized as follows:

“Basic Data Types”

The first section introduces basic data types such as int, float, bool, and str.

“Basic Data Structures”

The second section introduces the fundamental data structures of Python (e.g., list objects) and illustrates, among other things, control structures, functional programming approaches, and anonymous functions.

The aim of this chapter is to provide a general introduction to Python specifics when it comes to data types and structures. The reader equipped with a background from another programing language, say C or Matlab, should be able to easily grasp the differences that Python usage might bring along. The topics and idioms introduced here are important and fundamental for the chapters to come.

The chapter covers the following data types and structures:

Object type Meaning Used for


Integer value

Natural numbers


Floating-point number

Real numbers


Boolean value

Something true or false


String object

Character, word, text


Immutable container

Fixed set of objects, record


Mutable container

Changing set of objects


Mutable container

Key-value store


Mutable container

Collection of unique objects

Basic Data Types

Python is a dynamically ...

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