Returning the other value of the pair from a tuple, which has closest value to certain number

I have a list of tuples like this:

[(78, 10), (84, 11), (75, 12), (78, 13), (75, 14), (77, 15), (79, 16), (81, 17), (83, 18), (85, 19)]

How can I do like, if the first number in any of the tuples is closest/equal to a certain number, return the other pair value from that tuple?

for example in the list above:

certain number: 79
then it should return 16 from the above list.

Thanks!

>Solution :

You have a couple of options.

Method 1:

Iterate over the list and check for the smallest difference.

def return_closest_pair(data: list, target: int) -> int:
    closest, other = data[0]
    closest_diff = abs(closest - target)
    rest = iter(data[1:])
    for left, right in rest:
        diff = abs(left - target)
        if diff < closest_diff:
            closest, other = left, right
    return other

>>> return_closest_pair(data, 79)

Method 2:

Write a custom key for min function, as you had originally tried.

def find_closest_to(target):
    def comp(tup):
        left, right = tup
        return abs(left - target)
    return comp

>>> min(data, key=find_closest_to(79))[0]
16