4. Advanced techniques in list comprehension

Quiz: 0/5

In Python, list comprehension is not just about creating simple lists; it also allows you to apply functions and handle more complex conditions in a clean and concise way. Let’s break this down:

Applying functions within list comprehension

Sometimes, you want to apply a function to each item in your list. With list comprehension, this can be done in a very neat way. Here's the basic structure:

[function(item) for item in iterable]

• function: The function you want to apply to each item in the list.
• item: Each individual element from the iterable (like a list or a string).
• iterable: A sequence of items, such as a list, a string, or any iterable object.

Example: Converting strings to uppercase using str.upper()

Let’s say you have a list of words, and you want to convert them to uppercase:

words = ['apple', 'banana', 'cherry']
uppercase_words = [word.upper() for word in words]
print(uppercase_words)

Output:

['APPLE', 'BANANA', 'CHERRY']

Here, the upper() function is applied to each word in the list. The list comprehension makes this operation concise and easy to read.

List comprehension with multiple conditions

You can also use multiple conditions in a list comprehension to filter the items you want. The syntax looks like this:

[expression for item in iterable if condition1 and condition2]

This means you’ll only include items in your list that meet both conditions.

Example: Filtering numbers that are divisible by both 2 and 3

Let’s say you want to filter out only the numbers in a list that are divisible by both 2 and 3:

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 15]
filtered_numbers = [num for num in numbers if num % 2 == 0 and num % 3 == 0]
print(filtered_numbers)

Output:

[6, 12]

Here, the list comprehension only includes numbers that are divisible by both 2 and 3.

Why this is helpful:

• Using functions within list comprehensions makes your code cleaner, especially when you need to modify or transform the items.
• Multiple conditions allow you to filter the list based on several factors, all in one line!

This makes your code shorter, readable, and efficient, especially for beginners who are looking to simplify common tasks like transforming data or filtering lists.