Python Dictionaries

Python Dictionaries: An Essential Guide

Python dictionaries are one of the most essential data types that every programmer must know. Dictionaries in Python allow you to store data in key-value pairs and are incredibly useful in organizing and manipulating data. In this article, we are going to dive into the world of Python dictionaries, learning about their structure, methods, and flexible usage.

What is a Python Dictionary?

A dictionary in python is an unordered collection of key-value pairs, just like a dictionary in the real world, where a word is associated with its meaning. Each element in the dictionary consists of two parts: a key and a value. The key is unique and should be an immutable data type, while the value can be any data type, including strings, lists, sets, or even other dictionaries.

Creating a Python Dictionary

In Python, a dictionary can be created by enclosing a comma-separated list of key-value pairs inside curly braces. For example,

my_dict = {'name': 'John', 'age': 25, 'gender': 'male'}

This creates a dictionary with three keys, ‘name’, ‘age’, and ‘gender’, each with their respective values ‘John’, 25, and ‘male’.

Accessing Elements in a Python Dictionary

You can access elements in a Python dictionary using its keys. To access the value of a key in the dictionary, use the square bracket notation with the key name. For example,


will return the value ‘John’, and


will return 25.

Modifying Elements in a Python Dictionary

You can change the value associated with a given key in a Python dictionary by assigning a new value to the key. For example,

my_dict['age'] = 30

will change the value associated with the key ‘age’ from 25 to 30.

Dictionary Methods

Python provides several methods to manipulate dictionaries. Some of the most common methods include:

  • clear(): Removes all the key-value pairs from the dictionary.
  • copy(): Returns a shallow copy of the dictionary.
  • get(key, default): Returns the value of a key in the dictionary. If the key is not present, it returns the default value passed.
  • items(): Returns a list of key-value pair tuples.
  • keys(): Returns a list of keys in the dictionary.
  • pop(key, default): Removes and returns the value of a key. If the key is not present, it returns the default value passed.
  • values(): Returns a list of values in the dictionary.

Python Dictionary Comprehension

Python provides a shortcut method for creating dictionaries using dictionary comprehension. You can create a dictionary by defining a condition and an operation on one or more inputs. The syntax for dictionary comprehension is similar to list comprehension, as shown below.

squares = {x: x*x for x in range(1, 6)}

The above program will produce the following output.

{1: 1, 2: 4, 3: 9, 4: 16, 5: 25}


In summary, Python dictionaries are an essential data structure for storing and manipulating data using key-value pairs. We have covered the basics of Python dictionaries, including how to create them, accessing and modifying the elements within them, and using dictionary comprehension. With this knowledge, you are now ready to start using Python dictionaries in your programming projects.

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