Get all elements that only occur once

Question

Using LINQ, can I get a list of all int elements that only occur once?

For instance

{1,2,4,8,6,3,4,8,8,2}

would become

Answer 1

list.GroupBy(i => i)
    .Where(g => g.Count() == 1)
    .Select(g => g.First());

Answer 2

var result =
    from x in xs
    group xs by x into grp
    where grp.Count() == 1
    select grp.Key;

like that?

50seconds too late ... :/

Answer 3

Various Extension Methods you could use:

public static IEnumerable<T> WhereUnique<T>(this IEnumerable<T> items)
{
    return items.GroupBy(x => x).Where(x => x.Count() ==1).Select(x => x.First());
}

possibly slightly more performant, depending on the distribution of your data:

public static IEnumerable<T> WhereUnique<T>(this IEnumerable<T> items)
{
    return items.GroupBy(x => x).Where(x => !x.Skip(1).Any()).Select(x => x.First());
}

And WhereUniqueBy, which works similiar to MoreLinqs DistinctBy():

public static IEnumerable<T> WhereUniqueBy<T, TSelector>(this IEnumerable<T> items, Func<T, TSelector> func)
{
    return items.GroupBy(func).Where(x => x.Count() ==1).Select(x => x.First());
}