Dictionaries and Sets in Python

  1. Getting Started with Python
  2. Variables and Data Types in Python
  3. Basic Input and Output in Python
  4. Conditional Statements in Python
  5. Loops in Python
  6. Lists and Tuples in Python
  7. Dictionaries and Sets in Python
  8. Functions and Modules in Python
  9. Exception Handling in Python
  10. File Handling in Python
  11. Working with Dates and Times in Python
  12. List Comprehensions in Python

Welcome to the seventh article in our Python programming series for beginners! In this installment, we’ll explore two essential data structures in Python: dictionaries and sets. These versatile data structures play a significant role in organizing data and managing collections efficiently. Let’s dive into key-value pairs and unique collections. 

Introduction to Dictionaries and Sets

Dictionaries and sets are fundamental data structures in Python, each serving specific purposes:

– Dictionaries are used to store collections of key-value pairs. They are highly efficient for retrieving values based on keys.
– Sets are collections of unique elements. They are invaluable for tasks that require uniqueness, such as eliminating duplicate values from a list.

Dictionaries in Python

A dictionary in Python is an unordered collection of items where each item is stored as a key-value pair. Keys are unique, and they are used to access values. Dictionaries are defined using curly braces `{}` or the `dict()` constructor. Here’s how you can create a dictionary:

person = {
    "first_name": "John",
    "last_name": "Doe",
    "age": 30,
    "city": "New York"

Basic Dictionary Operations

Accessing Values
You can access values in a dictionary using square brackets and the key. For example, `person[“first_name”]` returns “John.”

Adding and Modifying Values
To add a new key-value pair or modify an existing one, simply assign a value to a key.

person["occupation"] = "Engineer"
person["age"] = 31  Modifying the age

Removing Key-Value Pairs
Use the `del` statement to remove a key-value pair by key.

del person["city"]

Sets in Python

A set in Python is an unordered collection of unique elements. Sets are defined using curly braces `{}` or the `set()` constructor. Here’s how you can create a set:

unique_numbers = {1, 2, 3, 4, 5}

Basic Set Operations

Adding and Removing Elements
You can add elements to a set using the `add()` method and remove elements using the `remove()` method.


Set Operations
Sets support various set operations like union, intersection, and difference.

set1 = {1, 2, 3}
set2 = {3, 4, 5}

union = set1.union(set2)           Union of set1 and set2
intersection = set1.intersection(set2) Intersection of set1 and set2
difference = set1.difference(set2)   Elements in set1 but not in set2

Practical Use Cases


Dictionaries are excellent for tasks such as:
– Storing configurations in key-value pairs.
– Counting the frequency of words in a text.
– Representing JSON data in Python.


Sets are useful for scenarios like:
– Removing duplicates from a list or a collection of data.
– Checking for the existence of unique items in a dataset.
– Performing mathematical set operations like union, intersection, and difference.


In this article, we’ve explored two vital data structures in Python: dictionaries and sets. Dictionaries efficiently store key-value pairs, facilitating data retrieval. Sets, on the other hand, manage collections of unique elements, which is invaluable for various programming tasks.

Understanding how to work with dictionaries and sets is essential for many programming tasks in Python. As you continue your Python journey, you’ll find these data structures invaluable for organizing data, eliminating duplicates, and efficiently accessing values.

In the next article of our series, we’ll delve into functions and modules, empowering you to organize your code into reusable and modular components. Stay curious, keep practicing, and happy coding!