转换iDictionary <TKey,TValue> 进入IDictionary <TSomeProperty, ICollection<TValue> &gt;

Question

I have a IDictionary<TKey, TValue> referencing my items by a TKey hash.

How could I group by those values by, say, the result of EquivalenceClass TKey.GetEquivalenceClass() ? The result would then fit into a IDictionary<EquivalenceClass, ICollection<TValue>>

A more concrete example, maybe: given

public enum PlayerPositionGroup {Attacker, Defender}
public class Player{
  public PlayerPositionGroup GetPositionGroup(){...}
}

turn

IDictionary<string, Player> SoccerPlayersByName

into

IDictionary<PlayerPositionGroup, ICollection<Player>>

Answer 1

How about this:

SoccerPlayersByName
.Values
.GroupBy(v => v.GetPositionGroup())
.ToDictionary(g => g.Key, g => g.ToArray());