| RankBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>) | Ranks each item in the sequence in descending ordering by a specified key using a default comparer |
| RankBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IComparer<TKey>) | Ranks each item in a sequence using a specified key and a caller-supplied comparer |