How to get distinct List from a custom list?

Question

I am using c# framework 3.5 ..

my class here

  public class KonumBilgisi
{

    public string Enlem { get; set; }
    public string Boylam { get; set; }
    public string KonumAdi { get; set; }
    public DateTime Tarih { get; set; }
    public byte SucTuruId { get; set; }

}

I have a list

List konumlar;

well, I want to get items that equal their enlem and boylam variables each other..

As you see on the photo below

I want to compate enlem and boylam and if its the equal I want to get them to different list..

I can do that with a loop but want to use LINQ but i couldnt do that. I used groupby but it doesnt wrong..

   var distinctList = konumlar.GroupBy(x => x.Enlem)
                        .Select(g => g.First())
                        .ToList().GroupBy(s=>s.Boylam).Select(g => g.First())
                        .ToList();

EDIT Actually I couldnt explain my quesion well..

maybe distinct is not right word.. I want to seperate items which are equals each other..

such as:

I will take pendik items in one list and others will be in konumlar but pendik items will be removed from konumlar list

EDIT 2

Okay I want to seperate the list like that

Answer 1

You are almost there - rather than using two separate GroupBy calls, use a single one, with a two-part key:

var distinctList = konumlar
    .GroupBy(s => new {s.Enlem, s.Boylam})
    .Select(g => g.First())
    .ToList();

EDIT : To get all items except the ones with duplicates, modify the query as follows:

var noPendiks = konumlar
    .GroupBy(s => new {s.Enlem, s.Boylam})
    .Where(g => g.Count() == 1)
    .Select(g => g.Single()) // You know there's only one
    .ToList();

The above will give you all items except the "pendik" ones. To get only the "pendik"s, use the query below:

var pendiks = konumlar
    .GroupBy(s => new {s.Enlem, s.Boylam})
    .Where(g => g.Count() > 1)
    .SelectMany(g => g)
    .ToList();

Answer 2

You can use the Distinct() Linq function, however, that does only work identical items. In case you want a DistinctBy() you can create a LinqExtensions class with a DistinctBy() method.

Here's one which I use quite common:

/// <summary>
///     Provides common extension methods on LINQ members.
/// </summary>
public static class LinqExtensions
{
    #region Members

    public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
    {
        HashSet<TKey> seenKeys = new HashSet<TKey>();
        foreach (TSource element in source)
        {
            if (seenKeys.Add(keySelector(element)))
            {
                yield return element;
            }
        }
    }

    #endregion Members
}

Use it as:

var distinctList = konumlar.DistinctBy(x => x.property && x.property2 && ...);

Kind regards