In Python, a list of dictionaries is a powerful way to organize and store multiple sets of key-value pairs. This structure combines two core data types: lists and dictionaries. A list can hold multiple dictionaries, where each dictionary stores data in the form of key-value pairs.
Basics of Lists of Dictionaries
A list of dictionaries is essentially a list that contains multiple dictionaries. Each dictionary in the list can store data like names, ages, or other related attributes. Here’s a simple example where we store data about users
In this case, the users list contains three dictionaries. Each dictionary has two key-value pairs ("name" and "age").
How to Access Data in a List of Dictionaries
To access values in a list of dictionaries, you need to first specify which dictionary you want to access (by its position in the list), and then specify the key within that dictionary.
Example:
Here, users[0] gives us the first dictionary, and ["name"] gives us the value associated with the key "name".
Example: Accessing all names using a loop
Updating Values in a List of Dictionaries
You can update values in any dictionary inside the list by referencing both the dictionary (using its index in the list) and the key you want to update.
Example:
Here, we updated the age of the second user, Jane, by accessing users[1] and changing the "age" key.
Practical Use Cases
Storing User Data
You can store details of multiple users in a list of dictionaries. Each dictionary holds the information of a single user, such as their name and age.
Filtering Data
You can use loops or list comprehensions to filter dictionaries in the list based on specific conditions.
Tips for Working with Lists of Dictionaries
Use Loops for Access
When working with lists of dictionaries, you’ll often use loops to access and manipulate the data. A for loop is perfect for this because it allows you to process each dictionary one by one.
Use List Comprehensions for Filtering
If you need to filter or extract specific dictionaries based on a condition, list comprehensions provide a concise and efficient way to do it.
Summary
A list of dictionaries in Python is a versatile way to store and manage multiple sets of key-value pairs. It allows you to organize data such as user details efficiently and access or update values easily. Using loops, list comprehensions, and safe access methods like .get(), you can effectively work with this data structure.