if the condition is met x *1.2 (apply change) else x (keep the value) in Python comprehension

Question

I have a big list of numbers like;

original_list = [20,10,15,56,80,200,47,12, 4,70,...]

I want to raise the numbers by 20 percent where they are less than 50, and keep the rest as they are in the list in the original order.

Is there any single comprehension method to make the second list without using function? perhaps;

revised_list =[x*1.2 for x in original_list if x < 50 else y for y in original_list]

Obscure solution: `revised_list = list(map(lambda x:x*[1,1.2][v<50], original_list))` — Matthias, Dec 06 '22 at 20:51
@Matthias: Yeah, I resisted the urge to suggest a similar approach using a listcomp (`lambda`s are the devil), `[x*(1, 1.2)[x < 50] for x in original_list]` (using a `tuple` to avoid it being reconstructed each time), or the similar `[x + x * .2 * (x < 50) for x in original_list]` that uses the boolean as its numeric value to zero out or keep the result of `x * .2`. The conditional expression is the sane way to go though. :-) — ShadowRanger, Dec 06 '22 at 21:01
Even if it's a duplicate, don't remove the content, this makes it worse. Eventually delete the answer, or just leave it as it is. This might help other users being routed to the duplicate. — mozway, Apr 27 '23 at 08:28

score 0 · Answer 1 · answered Dec 06 '22 at 20:45

You need to use the if/else conditional operator on the value production alone, not the whole attempt at a listcomp:

revised_list = [x*1.2 if x < 50 else x for x in original_list]

which only applies the multiplier if x < 50, and otherwise preserves the original x value.

score -1 · Answer 2 · answered Dec 06 '22 at 20:45

-1

To get a varying function you can use the python ternary expression:

revised_list = [x*1.2 if x < 50 else x for x in original_list]

answered Dec 06 '22 at 20:45

quamrana

2 Answers2