獲得使用LINQ

Question

唯一對象我有一個Person類：

Public Class Person 
{ 
public string Name {get; set;} 
public string Id {get; set;} 
} 

Public EqualityOnPerson : IEqualityComparer<Person> 
{ 
public bool Equals(PersonData x, PersonData y) 
    { 
     return x.Id == y.Id; 
    } 

    public int GetHashCode(Person obj) 
    { 
     return obj.Id.GetHashCode(); 
    } 

} 

我的人的列表與重複的ID對象是：

Person.Name = "ABC" 
Person.Id = "123" 

Person.Name = "CBA" 
Person.Id = "123" 

Person.Name = "DEF" 
Person.Id = "456" 

Person.Name = "GHI" 
Person.Id = "789" 

Person.Name = "JKL" 
Person.Id = "789" 

Person.Name = "MNO" 
Person.Id = "789" 

Person.Name = "PQR" 
Person.Id = "101" 

Person.Name = "STU" 
Person.Id = "102" 

使用不同會給

Person.Name = "CBA" 
Person.Id = "123" 

Person.Name = "DEF" 
Person.Id = "456" 

Person.Name = "GHI" 
Person.Id = "789" 

Person.Name = "PQR" 
Person.Id = "101" 

Person.Name = "STU" 
Person.Id = "102" 

我如何得到這個

Person.Name = "DEF" 
Person.Id = "456" 

Person.Name = "PQR" 
Person.Id = "101" 

Person.Name = "STU" 
Person.Id = "102" 

只有那些不重複的人物。

問候。

Answer 1

您需要組使用相等比較的人，然後選擇從羣體的人只有一個人：

var unduplicatedPersons = persons 
    .GroupBy(p => p, new EqualityOnPerson()) 
    .Where(g => g.Count() == 1) 
    .Select(g => g.Key); 

---

這裏的，如果需要可以有輕微的性能優勢專用的擴展方法（只是爲了好玩）：

public IEnumerable<T> DistinctOnly<T>(this IEnumerable<T> source, 
             IEqualityComparer<T> comparer) 
{ 
    HashSet<T> all = new HashSet<T>(comparer); 
    HashSet<T> distinct = new HashSet<T>(comparer); 
    foreach (T t in source) 
    { 
     if (all.Add(t)) 
      distinct.Add(t); 
     else 
      distinct.Remove(t); 
    } 
    return distinct; 
} 

Answer 2

var result = persons.Where(outer => 
    persons.Count(inner => inner.Id == outer.Id) < 2) 

這樣你就不會需要一個相等比較。