Get closest value in an Array

Question

int [] testArray = new int[3] { 5, 7, 8};

int check = 22;

var nearest = testArray.Min(x => Math.Abs(x - check));

Debug.Print(Convert.ToString(nearest));

I have the above code as an attempt to try and get the nearest number in the array closest to the check number, in this case 22.

The thing is that this always returns a positive value because of the Math.Abs but if I remove this the code completely fails. for example if the check number is 10, i want nearest to return -2 and not 2. This way I can just add the nearest value to the check number to get the proper value that's in the array.

I found something similiar upon searching, something called MoreLinq, that suggested using array.MinBy instead, however this method throws an error (says it doesn't exist)... Thanks

Answer 1

I would propose first order on min and take the first value. It's your nearest value and you could do with it what you want. For example calculate nearest-check

int[] testArray = new int[3] { 5, 7, 8 };

int check = 22;

var nearest = testArray.OrderBy(x => Math.Abs(x - check)).First();

Debug.Print(Convert.ToString(nearest-check));

Answer 2

Try testArray.Aggregate((min, next) => Math.Abs(next - check) > Math.Abs(min - check) ? min : next). It must be faster, than OrderBy().

Answer 3

If the source array is guaranteed to be sorted, you can use Array.BinarySearch. I guarantee that it will be faster than any LINQ solution you may find.

int[] arr = { 3, 5, 7 };
int idx = Array.BinarySearch(arr, 3);
int closest = idx < 0 ? arr[~idx] : arr[idx];