c#词典相交

Question

我有关于Linq/Lambda的问题以及以下问题:

我有两个词典,主要和次要......这两个词典被定义为Key = string,Value = int.如果KEYS与辅助字典相交,我需要修剪主字典.

即:

primaryDict = ["thing1", 33] ["thing2", 24] ["thing3", 21] ["thing4", 17] ["thing5", 12]

secondaryDict = ["thing1", 22] ["thing3", 20] ["thing4", 19] ["thing7", 17] ["thing9", 10]

resultDict = ["thing1", 33] ["thing3", 21] ["thing4", 17]

我的尝试:

resultDict = primaryDict.Keys.Intersect(secondaryDict.Keys).ToDictionary(t => t.Key, t.Value);

这显然不起作用,因为primaryDict.Keys.Intersect返回一个键列表...我将如何重新建立一个新词典,或者配对主词典？任何帮助,将不胜感激.

Answer 1

你可以这样做:

resultDict =  primaryDict.Keys.Intersect(secondaryDict.Keys)
                              .ToDictionary(t => t, t => primaryDict[t]);

或者,或者:

resultDict =  primaryDict.Where(x => secondaryDict.ContainsKey(x.Key))
                         .ToDictionary(x => x.Key, x => x.Value);

后者可能稍微更高效,因为避免创建一个抛弃集合(由Intersect方法生成的集合),并且不需要第二次按键访问primaryDict.

编辑(根据评论):

resultDict =  
primaryDict.Where(x => secondaryDict.ContainsKey(x.Key))
           .ToDictionary(x => x.Key, x => x.Value + secondaryDict[x.Key]);