结合Dictionary<A、B> + Dictionary<B、C>创建Dictionary<A、C>

Question

有什么很酷的快速方法可以用两个字典来创建第三个字典，以内部连接的方式将第一个字典的键映射到第二个字典的值？

Dictionary<A,B> dic1 = new Dictionary<A,B> {{a1,b1},{a2,b2},{a3,b3}};
Dictionary<B,C> dic2 = new Dictionary<B,C> {{b1,c1},{b2,c2},{b4,c4}};

Dictionary<A,C> dic3 = SomeFunction(dic1,dic2);
// dic3 = {{a1,c1},{a2,c2}}

Answer 1

您可以这样做来连接内部值

Dictionary<int, string> first = new Dictionary<int, string> { {1, "hello"}, {2, "world"}};

Dictionary<string, bool> second = 
    new Dictionary<string, bool> { { "hello", true }, {"world", false}};

var result = (from f in first
              join s in second on f.Value equals s.Key
              select new { f.Key, s.Value }).ToDictionary(x => x.Key, y => y.Value);

如果将结果转储出去，您将看到它是一个值为{1: true, 2: false}的字典

Answer 2

试试这个-

Dictionary<string, string> a, b, c;

//code to initialize the 3 dictionaries. a,b are original dictionaries and c is the new dictionary

c = ( from ak in a.Keys
    where b.ContainsKey( ak )
    select new KeyValuePair<string, string>( ak, b[ ak ] ) ).ToDictionary( d => d.Key, d=> d.Value );

Answer 3

public Dictionary<A,C> SomeFunction(dic1, dic2)
{
    var dic3 = new Dictionary<A,C>();
    foreach (var item in dic1)
    { 
         var item2 = dic2.Where(m=>m.Key == item.Value).FirstOrDefault(); 
         if (item2 != null) 
         {
             dic3.Add(item.Key, item2.Value);
         } 
    }
    return dic3
}

我相信这能满足你的需要