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Introduction
Real world Python
Python Data Structures
Discover the primary data structures in Python, including strings, lists, tuples, dictionaries, and sets.
By Kevin McAleer, 3 Minutes
Introduction
Data structures in Python are containers that organize and group data types together in different ways. This lesson will cover the primary data structures: strings, lists, tuples, dictionaries, and sets.
Learning Objectives
- Understand and use Python’s primary data structures: strings, lists, tuples, dictionaries, and sets.
Strings
Strings are sequences of characters, and they are created by enclosing characters in quotes. Python treats single quotes the same as double quotes1.
# A string in Python
greeting = "Hello, World!"
# Accessing characters in a string
first_char = greeting[0]
print(first_char) # Prints 'H'
# Strings are immutable
# The following line will raise an error
# greeting[0] = 'h'
Lists
Lists are ordered and mutable collections, which means you can replace, add or remove elements. Lists can contain items of different data types.
# Creating a list
numbers = [1, 2, 3, 4, 5]
# Accessing list items
first_number = numbers[0]
print(first_number) # Prints '1'
# Modifying a list
numbers[0] = 10
print(numbers) # Prints '[10, 2, 3, 4, 5]'
Tuples
Tuples are similar to lists but they are immutable, which means you can’t change elements of a tuple once it’s defined.
# Creating a tuple
coordinates = (10.0, 20.0)
# Accessing tuple items
x_coordinate = coordinates[0]
print(x_coordinate) # Prints '10.0'
# Tuples are immutable
# The following line will raise an error
# coordinates[0] = 20.0
Dictionaries
Dictionaries are unordered collections of key-value pairs. They are mutable and indexed by keys.
# Creating a dictionary
student = {'name': 'John', 'age': 15, 'grade': 'A'}
# Accessing dictionary values
name = student['name']
print(name) # Prints 'John'
# Modifying a dictionary
student['age'] = 16
print(student) # Prints "{'name': 'John', 'age': 16, 'grade': 'A'}"
Sets
Sets are unordered collections of unique elements. They are mutable, but they cannot contain mutable elements.
# Creating a set
fruits = {'apple', 'banana', 'cherry'}
# Checking if an element is in the set
print('apple' in fruits) # Prints 'True'
# Adding an element to the set
fruits.add('orange')
print(fruits) # May print "{'cherry', 'orange', 'banana', 'apple'}"
# Removing an element from the set
fruits.remove('apple')
print(fruits) # May print "{'cherry', 'orange', 'banana'}"
Summary
You’ve learned about Python’s main data structures and how to work with them. These structures are fundamental to organizing and storing data in your Python programs.
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