LINQ question ... need to get element with min value

Question

Im new to linq so i still struggle ....

I have a collection of controls (each has a Location of type Point). I need to remove the control with the lowest Y value (top control) from the collection.

An example would be most appreciated !

Answer 1

Something like this:

collection.Remove(collection.OrderBy(c => c.Location.Y).First());

The ordering is quite expensive, so depending on your use-case you could also find the item with the lowest value and then remove it:

collection.Remove(collection.First(c => c.Y == collection.Min(c2 => c2.Y)));

This enumerates the list up to three times, generally this should still be faster than the OrderBy, but if performance is important to you then measure first.

Answer 2

You just need to find the item and remove it, that's for sure. Remove is very clear, but while finding, you can use Aggregate method like this:

collection
   .Remove(collection
       .Aggregate((c1, c2) => c1.Point.Y < c2.Point.Y ? c1 : c2)
   )
);

Answer 3

collection.Remove( collection.Min( c => c.Y ));

Answer 4

Remember that LINQ stands for Language INtegreated Query. That is, it's meant to be used as a tool for querying, not for modifying collections.

That said, you could find the control you need to remove using LINQ. Then simply remove it the normal way.

// Let's say controls is a ControlCollection
var enumerable = controls.Cast<Control>();
int minimumY = enumerable.Min(c => c.Location.Y);
Control topControl = enumerable.Where(c => c.Location.Y == minimumY);

controls.Remove(topControl);

Answer 5

Ordering is more expensive. Just get the min value.

var lowest = (from c in collection
              where c.X == collection.Min(i => i.X)
              select c).FirstOrDefault();
collection.Remove(c);