Sort list by closest distances

Question

i'm working on a little application. When i'm adding a new destination i want to reorder my list by the closest positions of each other.

With the CalcDistance method i can calculate the distance between the current position and next position.

But i'm stuck on sorting my list. Any idea?

public class Transportcar
{
    public Destinations Start { get; set; }
    public Destinations End { get; set; }
    public int Deliveries { get; set; }

    List<Destinations> _destinations;

    public Transportcar()
    {
        _destinations = new List<Destinations>();

    }


    public void AddDestination(Destinations destination)
    {
        _destinations.Add(destination);
    }

    public IEnumerable<Destinations> Destinations {
        get {
            return _destinations.AsEnumerable();
        }
    }

    public double CalcDistance(Destinations Start, Destinations End)
    {
        //een ouwe man zei ooit: c^2 = a^2 + b^2 
        return Math.Sqrt(Math.Pow(Math.Abs(Start.X - End.X), 2) + Math.Pow(Math.Abs(Start.Y - End.Y), 2));
    }
}

public class Sendings     
{
    public List<Destinations> DestinationsTodo = new List<Destinations>();

    public void SortList()
    {
        DestinationsTodo = DestinationsTodo.OrderBy(x => x.X).ThenBy(x => x.Y).ToList();
    }

    }
}

Answer 1

In your situation, i totally suggest the SortedList class, but if you're sure to use the List , you can subtract all destination from deliver point, and then sort it.

List<Point> sub = new List<Point>();
_destinations.ForEach(item => sub.Add(new Point(item.X - deliver.X, item.Y - deliver.Y)));

sub.Sort((a, b) =>
{
    double d1 = Math.Pow(a.X, 2) + Math.Pow(a.Y, 2);
    double d2 = Math.Pow(b.X, 2) + Math.Pow(b.Y, 2);
    return d1.CompareTo(d2);
});

List<Point> sorted = new List<Point>();
sub.ForEach(item => sorted.Add(new Point(item.X + deliver.X, item.Y + deliver.Y)));

at the end, the sorted list is what you want.