Python Filter List of Dictionaries Based on Key Value

Python, a versatile and powerful programming language, offers multiple ways to manipulate and process data. When working with a list of dictionaries, you may often need to filter the data based on specific key-value pairs. In this article, we will explore three different methods to achieve this task: using list comprehension, the filter function, and a traditional for loop.

Python Filter List Of Dictionaries Based On Key Value

Below, are the methods to Python Filter List Of Dictionaries Based On Key Value.

• Using a For Loop
• Using List Comprehension
• Using the Filter Function

Create a List of Dictionaries

here, we are creating a List of Dictionaries.

Python3

data = [
    {'name': 'Alice', 'age': 25},
    {'name': 'Bob', 'age': 30},
    {'name': 'Charlie', 'age': 22},
    {'name': 'David', 'age': 35}
]

Filter List Of Dictionaries Based On Key-Value Using a For Loop

While list comprehensions and the filter the function provides concise solutions, using a for loop can be a more explicit and customizable approach. Here’s an example:

In this example, the for loop iterates through each dictionary in the data list and the if statement checks if the ‘age’ key has a value greater than 25. If true, the dictionary is appended to the filtered_data list.

Python3

# Filtering using a for loop
filtered_data = []
for entry in data:
    if entry['age'] > 25:
        filtered_data.append(entry)

print(filtered_data)

Output

[{'name': 'Bob', 'age': 30}, {'name': 'David', 'age': 35}]

Filter List Of Dictionaries Based On Key-Value Using List Comprehension

List comprehension is a concise and readable way to create lists in Python. It allows us to filter elements from an existing list based on certain conditions. Here’s an example of using list comprehension to filter a list of dictionaries:

In this example, the list comprehension iterates through each dictionary in the data list and includes only those dictionaries where the ‘age’ key has a value greater than 25.

Python3

# Filtering based on age greater than 25
filtered_data = [entry for entry in data if entry['age'] > 25]

print(filtered_data)

Output

[{'name': 'Bob', 'age': 30}, {'name': 'David', 'age': 35}]

Filter List Of Dictionaries Based On Key Value Using the Filter Function

The filter function is a built-in Python function that constructs an iterator from elements of an iterable for which a function returns true. To use it with a list of dictionaries, we need a filtering function. Here’s an example:

In this example, the filter_by_age function checks if the ‘age’ key in each dictionary is greater than 25. The filter function then applies this filtering function to each element in the data list.

Python3

# Filtering function
def filter_by_age(entry):
    return entry['age'] > 25

# Using filter function
filtered_data = list(filter(filter_by_age, data))

print(filtered_data)

Output

[{'name': 'Bob', 'age': 30}, {'name': 'David', 'age': 35}]