从.NET词典中删除与谓词匹配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.一种简单的方法如下:

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);

我不能直接删除foreach块中的项目的原因是，这将引发异常(集合已修改...")

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

我想执行以下操作:

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

但是Dictionary<>类没有像List<>类那样公开RemoveRemoveAll(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法是什么(无论是性能方面还是优雅方面)?

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

推荐答案

这是另一种方法

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

直接将代码放入列表中，可以避免出现枚举时删除"问题. .ToList()将在foreach真正开始之前强制进行枚举.

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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