Learn Python Dictionary and How to Create a Nested dictionary?

A nested dictionary is a collection of dictionaries inside a dictionary {key1:{key1:value,key2:value},…..}

Example:

travel_log = {
  "France": {"cities_visited": ["Paris", "Lille", "Dijon"], "total_visits": 12},
  "Germany": {"cities_visited": ["Berlin", "Hamburg", "Stuttgart"], "total_visits": 5},
}

Before discussing Nested Dictionary, Let’s talk about what is a dictionary

Dictionary is one of the data structures used in python to store data as a {key: value} structure and it is denoted as {}

How to declare an empty dictionary

The empty dictionary can be declared with empty curly brackets

empty_dictionary = {}

dictionary={"name":"Learn&Share"}

print(dictionary)

Try it Yourself

How to create a nested dictionary

Nesting Dictionary in a Dictionary using static declaration

travel_log = {
  "France": {"cities_visited": ["Paris", "Lille", "Dijon"], "total_visits": 12},
  "Germany": {"cities_visited": ["Berlin", "Hamburg", "Stuttgart"], "total_visits": 5},
}
print(travel_log)

Try it Yourself

Output

{'France': {'cities_visited': ['Paris', 'Lille', 'Dijon'], 'total_visits': 12}, 'Germany': {'cities_visited': ['Berlin', 'Hamburg', 'Stuttgart'], 'total_visits': 5}}

In the above example, We have a collection of dictionaries inside a dictionary

The outer dictionary has -> {“France”:”{“cities_visited”: [“Paris”, “Lille”, “Dijon”], “total_visits”: 12},}

The inner dictionary has -> “cities_visited”: [“Paris”, “Lille”, “Dijon”], “total_visits”: 12

How to create a nested dictionary using the function ()

Code Example:

travel_log = {
  "France": {"cities_visited": ["Paris", "Lille", "Dijon"], "total_visits": 12},
  "Germany": {"cities_visited": ["Berlin", "Hamburg", "Stuttgart"], "total_visits": 5},
}
def add_new_country_n(country,visit,cities):
    dir={"cities_visited":cities,"total_visits":visit}
    travel_log[country]=dir

add_new_country_n("Russia", 2, ["Moscow", "Saint Petersburg"])
print(travel_log)

Try it Yourself

Output

{'France': {'cities_visited': ['Paris', 'Lille', 'Dijon'], 'total_visits': 12}, 'Germany': {'cities_visited': ['Berlin', 'Hamburg', 'Stuttgart'], 'total_visits': 5}, 'Russia': {'cities_visited': ['Moscow', 'Saint Petersburg'], 'total_visits': 2}}

Explanation:

The function gets 3 inputs – outer dictionary key, inner dictionary key, and value
With the inner dictionary{ key: value}, We will create a dictionary

Then will add the created dictionary to the outer dictionary using the key

How to loop through a nested dictionary

Code Example:

travel_log = {
  "France": {"cities_visited": ["Paris", "Lille", "Dijon"], "total_visits": 12},
  "Germany": {"cities_visited": ["Berlin", "Hamburg", "Stuttgart"], "total_visits": 5},
}
for item in travel_log:
    print(item)
    print(travel_log[item])

Try it Yourself

Output:

France
{'cities_visited': ['Paris', 'Lille', 'Dijon'], 'total_visits': 12}
Germany
{'cities_visited': ['Berlin', 'Hamburg', 'Stuttgart'], 'total_visits': 5}

The outer dictionary key will not be printed by default, So we are printing it separately
For loop uses the key as an offset value to print the actual value

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