c# distinct code example

Example 1: C# .NET Core linq Distinct

var distinctUsers = allUsers
    .GroupBy(x => x.UserId)
    .Select(x => x.First())
    .ToList();

Example 2: c# distinct comparer multiple properties

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;
        }
    }
}

Example 3: linq distinct

var uniquePeople = from p in people
                   group p by new {p.ID} //or group by new {p.ID, p.Name, p.Whatever}
                   into mygroup
                   select mygroup.FirstOrDefault();

Example 4: c# distinct dictionary

var temp = _context.PlayerStats.Where(T => T.allianceId == _surf).Select(T => T.guildId).Distinct();
                var result = new Dictionary<string, string>();
                foreach (var item in temp)               
                    result[item] = _context.PlayerStats.FirstOrDefault(T => T.guildId == item).guildName;               
                return View(result);