Python | Nested Dictionary

Prerequisite – Python dictionary

A Dictionary in Python works similar to the Dictionary in the real world. Keys of a Dictionary must be unique and of immutable data type such as Strings, Integers and tuples, but the key-values can be repeated and be of any type.

Nested Dictionary: Nesting Dictionary means putting a dictionary inside another dictionary. Nesting is of great use as the kind of information we can model in programs is expanded greatly.

nested_dict = { 'dict1': {'key_A': 'value_A'}, 
                'dict2': {'key_B': 'value_B'}} 

# As shown in image 
  
# Creating a Nested Dictionary  
Dict = {1: 'Geeks', 2: 'For', 3: {'A' : 'Welcome', 'B' : 'To', 'C' : 'Geeks'}} 

Creating a Nested Dictionary

In Python, a Nested dictionary can be created by placing the comma-separated dictionaries enclosed withing braces.

# Empty nested dictionary 
Dict = { 'Dict1': { },  
         'Dict2': { }} 
print("Nested dictionary 1-") 
print(Dict) 
  
# Nested dictionary having same keys 
Dict = { 'Dict1': {'name': 'Ali', 'age': '19'}, 
         'Dict2': {'name': 'Bob', 'age': '25'}} 
print("\nNested dictionary 2-") 
print(Dict) 
  
# Nested dictionary of mixed dictionary keys 
Dict = { 'Dict1': {1: 'G', 2: 'F', 3: 'G'},  
         'Dict2': {'Name': 'Geeks', 1: [1, 2]} } 
print("\nNested dictionary 3-") 
print(Dict) 

Output:

Nested dictionary 1-
{'Dict1': {}, 'Dict2': {}}

Nested dictionary 2-
{'Dict1': {'name': 'Ali', 'age': '19'}, 'Dict2': {'name': 'Bob', 'age': '25'}}

Nested dictionary 3-
{'Dict1': {1: 'G', 2: 'F', 3: 'G'}, 'Dict2': {1: [1, 2], 'Name': 'Geeks'}}

Adding elements to a Nested Dictionary

Addition of elements to a nested Dictionary can be done in multiple ways. One way to add a dictionary in the Nested dictionary is to add values one be one, Nested_dict[dict][key] = 'value'. Another way is to add the whole dictionary in one go, Nested_dict[dict] = { 'key': 'value'}.

Dict = { } 
print("Initial nested dictionary:-") 
print(Dict) 
  
Dict['Dict1'] = {} 
  
# Adding elements one at a time  
Dict['Dict1']['name'] = 'Bob'
Dict['Dict1']['age'] = 21
print("\nAfter adding dictionary Dict1") 
print(Dict) 
  
# Adding whole dictionary 
Dict['Dict2'] = {'name': 'Cara', 'age': 25} 
print("\nAfter adding dictionary Dict1") 
print(Dict) 

Output:

Initial nested dictionary:-
{}

After adding dictionary Dict1
{'Dict1': {'age': 21, 'name': 'Bob'}}

After adding dictionary Dict1
{'Dict1': {'age': 21, 'name': 'Bob'}, 'Dict2': {'age': 25, 'name': 'Cara'}}

Access elements of a Nested Dictionary

In order to access the value of any key in nested dictionary, use indexing [] syntax.

# Nested dictionary having same keys 
Dict = { 'Dict1': {'name': 'Ali', 'age': '19'}, 
         'Dict2': {'name': 'Bob', 'age': '25'}} 
  
# Prints value corresponding to key 'name' in Dict1 
print(Dict['Dict1']['name']) 
  
# Prints value corresponding to key 'age' in Dict2 
print(Dict['Dict2']['age']) 

Output:

Ali
25

Deleting dictionaries from a Nested Dictionary

Deletion of dictionaries from a nested dictionary can be done either by using del keyword or by using pop() function.

Dict = {'Dict1': {'name': 'Ali', 'age': 19}, 
        'Dict2': {'name': 'Bob', 'age': 21}} 
print("Initial nested dictionary:-") 
print(Dict) 
  
# Deleting dictionary using del keyword  
print("\nDeleting Dict2:-") 
del Dict['Dict2'] 
print(Dict) 
  
# Deleting dictionary using pop function 
print("\nDeleting Dict1:-") 
Dict.pop('Dict1')  
print (Dict) 

Output:

Initial nested dictionary:-
{'Dict2': {'name': 'Bob', 'age': 21}, 'Dict1': {'name': 'Ali', 'age': 19}}

Deleting Dict2:-
{'Dict1': {'name': 'Ali', 'age': 19}}

Deleting Dict1:-
{}

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.

My Personal Notes

Oct	NOV	Dec
	12
2019	2020	2021

Creating a Nested Dictionary

Adding elements to a Nested Dictionary

Access elements of a Nested Dictionary

Deleting dictionaries from a Nested Dictionary

Recommended Posts: