Finding k closest numbers to a given number

Question

Say I have a list [1,2,3,4,5,6,7]. I want to find the 3 closest numbers to, say, 6.5. Then the returned value would be [5,6,7].

Finding one

Answer 1

You could compute distances, and sort:

[n for d, n in sorted((abs(x-myNumber), x) for x in myList)[:k]]

This does the following:

1. Create a sequence of tuples (d, x) where d is the distance to your target
2. Select the first k elements of that list
3. Extract just the number values from the result, discarding the distance