LINQ - order by distance (calculated value)

Question

What I would like is to loop through each item of a List in ascending order of distance (so the nearest targets are used first).

foreach (ShipCompartment enemyComp in enemy.ListOfCompartments.OrderBy(...))

The problem is that the distance is not a member of the class. Therefore I can't use:

foreach (ShipCompartment enemyComp in enemy.ListOfCompartments
    .OrderBy(c => c.Distance))

The code used to calculate distance is:

// Get distance between player and enemy compartments
float distanceToTarget = Vector2.Distance(playerComp.Position,
    enemyComp.Position);

How can I incorporate the calculation into OrderBy()? I've looked over here but it only returns the nearest Vector2.

Many thanks for your assistance.

Answer 1

The simple option would be to move the function call to the OrderBy call, so something like:

foreach (ShipCompartment enemyComp in enemy.ListOfCompartments.OrderBy(c => Vector2.Distance(playerComp.Position, c.Position)))

Answer 2

Your best solution if you need Distance generally (and not only for sorting) is to use Select to create a new structure that contains a definition of Distance and then use OrderBy. For example:

For the data structure:

class Coordinates
{
    public int Value { get; set; }
    public float Longitude { get; set; }
    public float Latitude { get; set; }
}

You call it like this:

foreach(var coordinate in coordinates.Select(x=> new 
    {
        Value = x.Value,
        Longitude = x.Longitude,
        Latitude = x.Latitude,
        Distance = x.Longitude + x.Latitude
    }).OrderBy(x=>x.Distance))
    Process(coordinate);