Retrieve largest negative number and smallest positive number from list

Question

Given a list of integers, e.g.:

lst = [-5, -1, -13, -11, 4, 8, 16, 32]

is there a Pythonic way of retrieving the largest negative number in the list (e.g. -1) and the smallest positive number (e.g. 4) in the list?

Solution

You can just use list comprehensions:

>>> some_list = [-5, -1, -13, -11, 4, 8, 16, 32]
>>> max([n for n in some_list if n<0])
-1
>>> min([n for n in some_list  if n>0])
4

Comments

[jonrsharpe]

Where should 0 end up, if present? And don't name your own list list.

[mgilson]

You can also use a generator expression here (and I'd advise against naming it l, maybe lst -- l looks too much like 1 in some fonts.

[Two-Bit Alchemist]

OK, I changed the variable name, though it's a bit beside the point for this. To use a generator expression instead change [] to (). I will leave the list form in the answer so it is clearer to anyone not familiar with it (like anyone with the same question as OP).

[mgilson]

To use a generator expression, you can just drop the [] entirely. e.g. max(n for n in some_list if n < 0) which looks a lot cleaner after you've gotten used to it.