Remove doubles from structs array

Question

I know 2 ways to remove doubles from an array of objects that support explicit comparing:

1. Using HashSet constructor and
2. Using LINQ's Distinct().

How to remove doubles from array of structs, comparing array members by a single field only? In other words, how to write the predicate, that could be used by Distinct().

Regards,

Answer 1

Well, you could implement IEqualityComparer<T> to pick out that field and use that for equality testing and hashing... or you could use DistinctBy which is in MoreLINQ.

Of course, you don't have to take a dependency on MoreLINQ really - you can implement it very simply:

public static IEnumerable<TSource> DistinctBy<TSource, TKey>
    (this IEnumerable<TSource> source,
     Func<TSource, TKey> keySelector)
{
    // TODO: Implement null argument checking :)

    HashSet<TKey> keys = new HashSet<TKey>();
    foreach (TSource element in source)
    {
        if (knownKeys.Add(keySelector(element)))
        {
            yield return element;
        }
    }
}