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.
Python3
nested_dict = { 'dict1': {'key_A': 'value_A'},
'dict2': {'key_B': 'value_B'}}
Python3
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 within braces.
Python3
Dict =
{ 'Dict1': { },
'Dict2': { }}
print["Nested dictionary 1-"]
print[Dict]
Dict = { 'Dict1': {'name': 'Ali', 'age': '19'},
'Dict2': {'name': 'Bob', 'age': '25'}}
print["\nNested dictionary 2-"]
print[Dict]
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’}.
Python3
Dict = { }
print["Initial nested dictionary:-"]
print[Dict]
Dict['Dict1'] = {}
Dict['Dict1']['name'] =
'Bob'
Dict['Dict1']['age'] = 21
print["\nAfter adding dictionary Dict1"]
print[Dict]
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.
Python3
Dict = { 'Dict1': {'name': 'Ali', 'age': '19'},
'Dict2': {'name': 'Bob', 'age': '25'}}
print[Dict['Dict1']['name']]
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.
Python3
Dict = {'Dict1': {'name': 'Ali', 'age': 19},
'Dict2': {'name': 'Bob', 'age': 21}}
print["Initial nested dictionary:-"]
print[Dict]
print["\nDeleting Dict2:-"]
del Dict['Dict2']
print[Dict]
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:-
{}