LINQ Distinct 不使用 IEqualityComparer？

Question

我有以下型号：

public class Word {
      public string Original { get; set; }
      public string Normalized { get; set; }
      public string Root { get; set; }
      public string Subroot { get; set; }
      public Regex SubrootRegex { get; set; }
}

我创建了以下三个IEqualityComparer<Word>:

public class NormalizedWordComparer : IEqualityComparer<Word> {
     public bool Equals(Word x, Word y) {
          return x.Normalized == y.Normalized;
     }
     public int GetHashCode(Word obj) {
          return obj.GetHashCode();
     }
}

public class RootWordComparer : IEqualityComparer<Word> {
     public bool Equals(Word x, Word y) {
          return x.Root == y.Root;
     }
     public int GetHashCode(Word obj) {
          return obj.GetHashCode();
     }
}

public class SubrootWordComparer : IEqualityComparer<Word> {
     public bool Equals(Word x, Word y) {
          return x.Subroot == y.Subroot;
     }
     public int GetHashCode(Word obj) {
          return obj.GetHashCode();
     }
}

在另一个 class 中，我正在尝试执行以下操作：

_normalizedWords = ConfigurationFacade.Words.Select(w => {
     Word word = new Word() { Original = w };
     word.Normalized = Normalize(word, _filters);
     word.Root = GetRoot(word.Normalized, ConfigurationFacade.WordRootPercentage);
     word.Subroot = GetRoot(word.Root, ConfigurationFacade.WordSubrootPercentage);
     word.SubrootRegex = null; //Complicated regex here
     return word;
}).Distinct(new NormalizedWordComparer());

_wordRoots = _normalizedWords.Distinct(new RootWordComparer());
_wordSubroots = _wordRoots.Distinct(new SubrootWordComparer());

然而，_normalizedWords、_wordRoots 和 _wordSubroots 都以相同数量的元素结束，就好像 Distinct() 方法不起作用或比较器一样被忽略了。

我用调试器检查了元素，Root值相同的有很多，所以_wordRoots中应该只有一个，但事实并非如此，它们不会被删除或过滤。

为什么我的 Distinct() 不工作？

Answer 1

Why is my Distinct() not working?

因为Distinct 首先检查散列码（因为这是快速检查两个对象是否可以相等) 并且然后调用 Equals。由于您的 GetHashCode 实现都是相同的（并且与您的 Equals 方法不对应），因此 Distinct 没有像您期望的那样工作。

更改您的 GetHashCode 方法以对应 Equals:

public class NormalizedWordComparer : IEqualityComparer<Word> {
     public bool Equals(Word x, Word y) {
          return x.Normalized == y.Normalized;
     }
     public int GetHashCode(Word obj) {
          return obj.Normalized.GetHashCode();
     }
}

public class RootWordComparer: IEqualityComparer<Word> {
     public bool Equals(Word x, Word y) {
          return x.Root == y.Root;
     }
     public int GetHashCode(Word obj) {
          return obj.Root.GetHashCode();
     }
}

public class SubrootWordComparer : IEqualityComparer<Word> {
     public bool Equals(Word x, Word y) {
          return x.Subroot == y.Subroot;
     }
     public int GetHashCode(Word obj) {
          return obj.Subroot.GetHashCode();
     }
}

LINQ Distinct 不使用 IEqualityComparer？

LINQ Distinct not using the IEqualityComparer?

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