What Is Dictionary Data Structure Python?


Larry Thompson

In Python, a dictionary is a powerful data structure that allows you to store and retrieve data in an organized manner. It is also known as an associative array or hash table in other programming languages. A dictionary consists of key-value pairs, where each key is unique and associated with a value.

Creating a Dictionary

To create a dictionary in Python, you can use curly braces ({}) or the built-in dict() function. Here’s an example:

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

In this example, we have created a dictionary called my_dict. It has two key-value pairs: ‘name’ with the value ‘John’ and ‘age’ with the value 25.

Accessing Values in a Dictionary

You can access the values of a dictionary by referencing its keys. To do this, you can use square brackets ([]). Here’s how:

name = my_dict['name']
age = my_dict['age']

This will output:


Modifying Values in a Dictionary

If you want to modify the value associated with a specific key in a dictionary, you can simply assign a new value to that key. Here’s an example:

my_dict['age'] = 30

This will update the value of the ‘age’ key to 30 and print the updated dictionary:

{'name': 'John', 'age': 30}

Dictionary Methods

Python provides several useful methods for working with dictionaries:

  • keys(): Returns a list of all the keys in the dictionary.
  • values(): Returns a list of all the values in the dictionary.
  • items(): Returns a list of all the key-value pairs in the dictionary as tuples.
  • get(key): Returns the value associated with a specific key. If the key does not exist, it returns None or a default value that you can specify.
  • pop(key): Removes and returns the value associated with a specific key.

Here’s an example that demonstrates some of these methods:

['name', 'age']
['John', 30]
[('name', 'John'), ('age', 30)]
{'name': 'John'}

Nested Dictionaries

A dictionary can also contain other dictionaries as values, creating a nested structure. This allows you to represent complex data relationships. Here’s an example:

my_dict = {'person1': {'name': 'John', 'age': 25}, 'person2': {'name': 'Jane', 'age': 30}}


In Python, dictionaries are a powerful data structure that allows you to store and retrieve data using key-value pairs. They provide a flexible and efficient way to organize and manipulate data. By understanding how dictionaries work and utilizing their methods, you can take full advantage of this data structure in your Python programs.

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