从 .NET 字典中删除匹配谓词的多个项目的最佳方法? [英] Best way to remove multiple items matching a predicate from a .NET Dictionary?

问题描述

我需要从字典中删除多个项目.一个简单的方法如下:

I need to remove multiple items from a Dictionary. A simple way to do that is as follows :

  List<string> keystoremove= new List<string>();
  foreach (KeyValuePair<string,object> k in MyCollection)
     if (k.Value.Member==foo)
        keystoremove.Add(k.Key);
  foreach (string s in keystoremove)
        MyCollection.Remove(s);

之所以不能直接Remove foreach块中的items是因为这样会抛出异常("Collection was modified...")

The reason why I can't directly Remove the items in the foreach block is that this would throw an Exception ("Collection was modified...")

我想做以下事情:

 MyCollection.RemoveAll(x =>x.Member==foo)

但是 Dictionary<> 类没有像 List<> 类那样公开 RemoveAll(Predicate<> Match) 方法.

But the Dictionary<> class doesn't expose a RemoveAll(Predicate<> Match) method, like the List<> Class does.

做到这一点的最佳方式是什么(性能方面和优雅方面)?

What's the best way (both performance wise and elegant wise) to do that?

推荐答案

这是另一种方式

foreach ( var s in MyCollection.Where(kv => kv.Value.Member == foo).ToList() ) {
  MyCollection.Remove(s.Key);
}

直接将代码推入列表可以避免枚举时删除"问题..ToList() 将在 foreach 真正开始之前强制枚举.

Pushing the code into a list directly allows you to avoid the "removing while enumerating" problem. The .ToList() will force the enumeration before the foreach really starts.

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