Python comprehensions, let's talk about them

Hi there! I would like to share some thoughts …

Recently I got a call from a recruiter and was asked about my work experience and so on.
And one question was do you use comprehensions and how frequently?

Hm… Yeah!
I know about them and sometimes I use them but!
There is one rule PEP20 - The Zen of Python, sentence 3 says: “Simple is better than complex” (sometimes I say it when I see a regular expression).
It should be a balance when and how to use them.

Disclaimer! If you love complexity or an adept of Python comprehensions, stop reading, just skip next piece of information.

Let’s write a simple function which creates an output list with only even numbers:

Second function will do the same but we will use the comprehensions:

Let’s compare a bytecode for each function:

What we got. In the second function, we saved 3 lines of code, but in bytecode, we get the same 76 lines of bytecode.

How about run time?

Hm! Looks like the first function has 4 extra calls during an execution.
It’s definitely will save runtime for a huge amount of data calculation.

My message is - in code, you can use simple code or use the comprehensions but it shouldn’t be against readability, maintainability, and definitely performance (!).

P/S: I should have compared different types of Python comprehensions and measured runtime for each type but it’s in another article ;)