Mastodawn

librejoe Jun 25, 2024

Why can't I append to list inside of a list comprehension?

Why can't I append to list inside of a list comprehension? - Lemmy.World

I’m new to programming a bit, and am learning python so I can learn flask, using the python crash course book. I was learning about list comprehension but it briefly talks about it. If I do > list[list.append(value) for value in range(1, 20)]> it doesn’t work. Would this be some sort of recursive expression that is not possible?

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Eager Eagle

List comprehensions return a new list. For the sake of code clarity, you probably shouldn’t change a second list from within a list comprehension. If you’re trying to concatenate two lists, you can do so in a second line:

a = list(range(10)) b = [ value for value in range(5) ] a.extend(b) # a has 15 elements print(a)