Why is there no Linq method to return distinct values by a predicate?

Question

I want to get the distinct values in a list, but not by the standard equality comparison.

What I want to do is something like this:

return myList.Dis         


        

Answer 1

Jon, your solution is pretty good. One minor change though. I don't think we need EqualityComparer.Default in there. Here is my solution (ofcourse the starting point was Jon Skeet's solution)

    public static IEnumerable DistinctBy(this IEnumerable source, Func keySelector)
    {
        //TODO All arg checks
        HashSet keys = new HashSet();
        foreach (T item in source)
        {
            TKey key = keySelector(item);
            if (!keys.Contains(key))
            {
                keys.Add(key);
                yield return item;
            }
        }
    }