How to take N elements from the end of a list in Python? N >= zero

Question

The interval for N includes zero, so a trivial slicing lst[-n:] is not a solution here. I am looking for something like takeright from Scala.

Current solution:

lst = [1, 2, 3]
print(lst[len(lst) - n :])

What does "N includes zero" mean? its unclear what you're asking, or why `lst[-n:]` isn't a solution — Sayse, Jan 11 '20 at 19:10
@Sayse What they probably mean: if `n` is 0, they want an enpty list. `lst[-n:]` is in this case `lst[0:]`, which is a copy of the entire list. — glglgl, Jan 11 '20 at 19:11
@glglgl - Fair enough. Possible duplicate: [Python negative zero slicing](https://stackoverflow.com/q/11337941/1324033) — Sayse, Jan 11 '20 at 19:21

score 3 · Accepted Answer · answered Jan 11 '20 at 19:10

3

According to your requirements, you only have to deal with the special case n == 0.

lst = [1, 2, 3]
print(lst[-n:] if n else [])

is probably the shortest resp. easiest you can have.

If you don't like that, you probably should stick with your solution.

answered Jan 11 '20 at 19:10

glglgl

Aren't any tools for this kind of thing there in Python functional libraries? – dawid Jan 12 '20 at 20:42

abhiarora · Answer 2 · 2020-01-11T19:24:22.130

1

N includes zero, so a trivial slicing lst[-n:] is not a solution here.

If you want to handle the case when n is or less than 0, then you can use ternary operator in Python. Like this:

result = li[-n:] if n > 0 else []

Or

You can use your solution as mentioned in this answer too! (Thanks to @glglgl)

edited Jan 11 '20 at 19:24

answered Jan 11 '20 at 19:17

abhiarora

2 Answers2