Is Dictionary a Mutable Data Structure?


Scott Campbell

In Python, a dictionary is a built-in data structure that stores key-value pairs. It is commonly used to represent mappings between objects.

One question that often arises is whether a dictionary is a mutable data structure. Let’s explore this concept further.

Mutable vs. Immutable Data Structures

Before we delve into the mutability of dictionaries, let’s quickly understand the difference between mutable and immutable data structures.


  • An immutable data structure cannot be modified once it is created.
  • Any operation performed on an immutable object returns a new object with the updated value.
  • Examples of immutable data structures include strings, numbers, and tuples.


  • A mutable data structure can be modified after it is created.
  • Operations can directly modify the contents of a mutable object without creating a new object.
  • Examples of mutable data structures include lists, sets, and dictionaries.

Dictionaries as Mutable Data Structures

Dictionaries are indeed mutable in Python. This means that you can modify their contents after they are created. Let’s look at some examples to understand how this works:

Adding and Modifying Elements

To add or modify an element in a dictionary, you can simply assign a value to a specific key:

my_dict = {'name': 'John', 'age': 25}
my_dict['name'] = 'Alice'  # Modifying existing key
my_dict['city'] = 'New York'  # Adding new key-value pair

The output of the above code will be:

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Removing Elements

You can also remove elements from a dictionary using the del keyword:

my_dict = {'name': 'John', 'age': 25, 'city': 'New York'}
del my_dict['age']

{'name': 'John', 'city': 'New York'}


In conclusion, dictionaries are mutable data structures in Python. This means that you can add, modify, and remove elements from a dictionary after it is created. Understanding the mutability of dictionaries is important when working with complex data structures and performing operations on them.

By incorporating mutability into your programming knowledge, you can better leverage dictionaries to efficiently store and manipulate data in Python.

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