Question

I want to sort a list based on how close a number in the list is to a given number. So for example:

target_list = [1,2,8,20]
number = 4

then probably sorted list is [2,1,8,20] since:

   4-2 = 2
   4-1 = 3
 |4-8| = 4
|4-20| = 16

In case of collision, I don’t really care which one comes first but then I am trying to sort the list on the basis of this distance metric.
What is the best (and pythonic) way to do this?

Answer 1

You can use the key parameter of the sorted function

>>> target_list = [1,2,8,20]
>>> sorted(target_list, key=lambda x: abs(4-x))
[2, 1, 8, 20]

Or if you want to sort it in place, even the list sort method accepts a key.

>>> target_list.sort(key=lambda x: abs(4-x))
>>> target_list
[2, 1, 8, 20]