将IEnumerable <t>转换为LookUp <t，k> </t，k> </t>

Question

我有一个函数返回以下类的IEnumerable

public class User
{
  public string UserName { get; set; }
  public IList<string> MemberOf { get; set; }
}

如何将IEnumerable转换为LookUp
 键将是用户名，值是memberOf列表

Answer 1

IEnumerable<User> seq = ...;    
ILookup<string, IList<string>> lookup = seq.ToLookup(u => u.UserName, u => u.MemberOf);