Convert Dictionary of Dictionaries to Python List of Dictionaries

Dictionaries are powerful data structures in Python, allowing the storage of key-value pairs. Sometimes, we encounter scenarios where we have a dictionary of dictionaries, and we need to convert it into a list of dictionaries for easier manipulation or processing. In this article, we’ll explore five different methods to achieve this conversion, each with its advantages and use cases.

Converting A Dictionary Of Dictionaries To A List Of Dictionaries

Below, are the methods of Converting A Dictionary Of Dictionaries To A List Of Dictionaries in Python.

• Using List Comprehension
• Using the `map()` Function
• Using `copy` & `update` Methods
• Using Enumerate() Function

Create Dictionary

This dictionary represents information about three individuals, with each person having attributes like name, age, and city.

Python3

data = {
    'person1': {'name': 'Alice', 'age': 30, 'city': 'New York'},
    'person2': {'name': 'Bob', 'age': 25, 'city': 'San Francisco'},
    'person3': {'name': 'Charlie', 'age': 35, 'city': 'Los Angeles'}
}

Convert A Dictionary Of Dictionaries To A List Using List Comprehension

In this example, the below code initializes a list of dictionaries by using a list comprehension to extract key-value pairs from each inner dictionary within the original ‘data’ dictionary.

Python3

list_of_dicts = [{key: value for key, value in nested_dict.items()} for nested_dict in data.values()]
print(type(data))
print("Result:", list_of_dicts)
print(type(list_of_dicts))

Output

<class 'dict'>
Result: [{'name': 'Alice', 'age': 30, 'city': 'New York'}, 
{'name': 'Bob', 'age': 25, 'city': 'San Francisco'}, 
{'name': 'Charlie', 'age': 35, 'city': 'Los Angeles'}]
<class 'list'>

Convert A Dictionary Of Dictionaries To A List Using the `map` Function

In this example, in below code, the `map` function is employed to convert the values of the ‘data’ dictionary into individual dictionaries, resulting in a ‘list_of_dicts.’ The code then prints the type of the original ‘data’ dictionary, displays the result.

Python3

# Using the `map` Function
list_of_dicts = list(map(dict, data.values()))

print(type(data))
print(" Result:", list_of_dicts)
print(type(list_of_dicts))

Output

<class 'dict'>
Result: [{'name': 'Alice', 'age': 30, 'city': 'New York'}, 
{'name': 'Bob', 'age': 25, 'city': 'San Francisco'}, 
{'name': 'Charlie', 'age': 35, 'city': 'Los Angeles'}]
<class 'list'>

Convert A Dictionary Of Dictionaries To A List Using `copy` and `update`

In this example, iin below code a new list of dictionaries, ‘list_of_dicts,’ is created by iterating through the items of the original ‘data’ dictionary. For each inner dictionary, a copy is made, and the ‘id’ key-value pair is added using the `update` method.

Python3

#Using `copy` and `update` Methods
list_of_dicts = []
for key, value in data.items():
    temp_dict = value.copy()
    temp_dict.update({'id': key})
    list_of_dicts.append(temp_dict)

print(type(data))
print("Result:", list_of_dicts)
print(type(list_of_dicts))

Output

<class 'dict'>
Result: [{'name': 'Alice', 'age': 30, 'city': 'New York'}, 
{'name': 'Bob', 'age': 25, 'city': 'San Francisco'}, 
{'name': 'Charlie', 'age': 35, 'city': 'Los Angeles'}]
<class 'list'>

Convert A Dictionary Of Dictionaries To A List Using Enumerate() Function

In this example, in below code the `enumerate` function is used with a list comprehension to create a ‘list_of_dicts.’ Each inner dictionary is augmented with the additional key-value pair ‘id’: key, where the key is the enumeration index starting from 1.

Python3

# Using Enumerate
list_of_dicts = [{**value, 'id': key} for key, value in enumerate(data.values(), 1)]

print(type(data))
print("Result:", list_of_dicts)
print(type(list_of_dicts))

Output

<class 'dict'>
Result: [{'name': 'Alice', 'age': 30, 'city': 'New York'}, 
{'name': 'Bob', 'age': 25, 'city': 'San Francisco'}, 
{'name': 'Charlie', 'age': 35, 'city': 'Los Angeles'}]
<class 'list'>