How to define a Python dictionary within dictionary?

A Dictionary in Python is a mutable, unordered collection of data in a key-value format. A dictionary can also contain another dictionary as a value, and this is known as a Nested Dictionary or a dictionary within a dictionary.

In this article, we are going to explore all the different ways to use a dictionary within a dictionary in Python.

Syntax to define a Dictionary within another

Following is the syntax of creating a Dictionary within another Dictionary in Python -

outer_dict = { 'key1': { 'inner_key1': 'value1', 'inner_key2': 'value2' }, 'key2': { 'inner_key1': 'value3', 'inner_key2': 'value4' } } 

Note: We can access nested dictionary elements using multiple keys as outer_dict['key1']['inner_key1'].

Example-1: Create a basic Dictionary

In this example, we are going to create a basic Dictionary and then see how to create a Dictionary within a Dictionary -

# Creating a Dictionary mydict = { 'name': 'Riyaansh', 'age': 30, 'department': 'HR' } # Displaying the Dictionary print("Dictionary = ", mydict) # Length of the Dictionary print("Dictionary Length = ", len(mydict)) 

Following is the output of the above program -

Dictionary = {'name': 'Riyaansh', 'age': 30, 'department': 'HR'} Dictionary Length = 3 

Creating a Dictionary within a Dictionary

Here in this example, we will create a dictionary where each key maps to another dictionary that holds employee details -

# Creating a Dictionary within a Dictionary employee_data = { 'emp1': {'name': 'Riyaansh', 'age': 30, 'department': 'HR'}, 'emp2': {'name': 'Anil', 'age': 25, 'department': 'Engineering'}, 'emp3': {'name': 'Karthikeya', 'age': 28, 'department': 'Marketing'} } # Displaying the Dictionary print("Employee Data = ", employee_data) # Length of the Outer Dictionary print("Total Employees = ", len(employee_data)) 

Below is the output of the above program -

Employee Data = {'emp1': {'name': 'Riyaansh', 'age': 30, 'department': 'HR'}, 'emp2': {'name': 'Anil', 'age': 25, 'department': 'Engineering'}, 'emp3': {'name': 'Karthikeya', 'age': 28, 'department': 'Marketing'}} Total Employees = 3 

Accessing a Dictionary within a Dictionary

We can access the inner dictionary by using the keys of the dictionary. Here is an example of accessing the Dictionary within a Dictionary -

# Creating a Dictionary within a Dictionary employee_data = { 'emp1': {'name': 'Riyaansh', 'age': 30, 'department': 'HR'}, 'emp2': {'name': 'Anil', 'age': 25, 'department': 'Engineering'}, 'emp3': {'name': 'Karthikeya', 'age': 28, 'department': 'Marketing'} } # Accessing inner dictionary print("emp2 Name = ", employee_data['emp2']['name']) print("emp3 Department = ", employee_data['emp3']['department']) 

Below is the output of the above program -

emp2 Name = Anil emp3 Department = Marketing 

Adding a New Inner Dictionary

In this example, we will add a new dictionary entry to our existing dictionary using a new key and value pair by using the assignment operator -

# Creating a Dictionary within a Dictionary employee_data = { 'emp1': {'name': 'Riyaansh', 'age': 30, 'department': 'HR'}, 'emp2': {'name': 'Anil', 'age': 25, 'department': 'Engineering'}, 'emp3': {'name': 'Karthikeya', 'age': 28, 'department': 'Marketing'} } # Adding new employee employee_data['emp4'] = {'name': 'Niharikaa', 'age': 32, 'department': 'Finance'} # Display the new employee record print("emp4 Record = ", employee_data['emp4']) 

Below is the output of the above program -

emp4 Record = {'name': 'Niharikaa', 'age': 32, 'department': 'Finance'} 

Looping through a Dictionary within a Dictionary

In this example, we will iterate over the outer dictionary and then over each inner dictionary to display complete all details of the employee information -

# Creating a Dictionary within a Dictionary employee_data = { 'emp1': {'name': 'Riyaansh', 'age': 30, 'department': 'HR'}, 'emp2': {'name': 'Anil', 'age': 25, 'department': 'Engineering'}, 'emp3': {'name': 'Karthikeya', 'age': 28, 'department': 'Marketing'}, 'emp4': {'name': 'Niharikaa', 'age': 32, 'department': 'Finance'} } # Looping through nested dictionaries for emp_id, emp_info in employee_data.items(): print(f"Employee ID: {emp_id}") for key, value in emp_info.items(): print(f" {key}: {value}") 

Below is the output of the above program -

Employee ID: emp1 name: Riyaansh age: 30 department: HR Employee ID: emp2 name: Anil age: 25 department: Engineering Employee ID: emp3 name: Karthikeya age: 28 department: Marketing Employee ID: emp4 name: Niharikaa age: 32 department: Finance 

Access Specific Inner Dictionary Keys

We can access the specific values from the inner dictionary using exact outer key of the dictionary -

employee_data = { 'emp1': {'name': 'Riyaansh', 'age': 30, 'department': 'HR'}, 'emp2': {'name': 'Anil', 'age': 25, 'department': 'Engineering'}, 'emp3': {'name': 'Karthikeya', 'age': 28, 'department': 'Marketing'}, 'emp4': {'name': 'Niharikaa', 'age': 32, 'department': 'Finance'} } # Specific access print("emp1 Age = ", employee_data['emp1']['age']) print("emp4 Department = ", employee_data['emp4']['department'])

Following is the output of the above program -

emp1 Age = 30 emp4 Department = Finance