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Python List Comprehension: One-Liner For Loops

Comprehensions offer a smooth approach for creating new sequences in a concise and readable way.

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Python List Comprehension makes it possible to write concise one-liners for loops.

For instance, you can use a comprehension to replace this:

With this:

There are actually 4 different comprehensions in Python for the main collection types:

• List Comprehensions
• Dictionary Comprehensions
• Set Comprehensions
• Generator Comprehensions

Python List Comprehension

Here is the general structure for list comprehension for your convenience:

[expression for var in input_list if condition]

Where the if condition part is optional

Example

Say you have a list of numbers and you want to exclude all the negatives. Using a for loop to iterate over the list of numbers is nothing new:

Output:

[1, 3, 5]

However, if you want to bring it to the next level, you can make this whole for loop shorter by using list comprehension: