Assigning a pair of variables to the min/max of two variables in Python

Question

I would like to assign two quantities to the variables min and max, depending on their value. Suppose f is a function which returns an integer value. Is there any way I can do something like

min, max = f(1), f(2)

which accounts for the values of f(1) and f(2)? Clearly the above assigns f(1) to min and f(2) to max regardless of their value.

`... = sorted((f(1), f(2)))` if I'm understanding this right? — miradulo, May 12 '18 at 18:29

miradulo · Accepted Answer · 2018-05-12T19:01:05.447

You can just sort an iterable of the return values before assigning them to min_v and max_v.

min_v, max_v = sorted((f(1), f(2)))

If you had a small iterable of return values (but more than 2), using extended iterable unpacking might be alright.

min_v, *_, max_v = sorted(map(f, some_small_list))

But of course if you applied f to a list of any considerable length, it is far more efficient to pluck out the min and max with the built-ins (which you shouldn't shadow) rather than sort and unpack.

score -2 · Answer 2 · answered May 12 '18 at 18:32

-2

You can do something like:

min, max = (f(1),(f2)) if f(1)<f(2) else (f(2),f(1))

If this is what you were looking for.

answered May 12 '18 at 18:32

sourabh

48
5

3

this calls the functions twice – juanpa.arrivillaga May 12 '18 at 18:37
1

For those interested, this is the type of issue [PEP-572](https://www.python.org/dev/peps/pep-0572/) tries to address. – chepner May 12 '18 at 19:00
@chepner how would an assignment expression be used here? – juanpa.arrivillaga May 12 '18 at 19:02
1

I assume something like `min, max = a, b if a:=f(1) < b:=f(2) else b, a` (assuming `:=` wins out). Or `min, max = a, b if a < b else b, a given (a, b) = (f(1), f(2))`. (Plus or minus some parentheses) – chepner May 12 '18 at 19:08

Assigning a pair of variables to the min/max of two variables in Python

2 Answers2