C#:将Dictionary <String,String>转换为Dictionary <String,Dictionary <String,String >>

Question

第一个Dictionary就像

        Dictionary<String, String> ParentDict = new Dictionary<String, String>();
        ParentDict.Add("A_1", "1");
        ParentDict.Add("A_2", "2");
        ParentDict.Add("B_1", "3");
        ParentDict.Add("B_2", "4"); 
        ParentDict.Add("C_1", "5");

我需要将其转换为新的 Dictionary<String, Dictionary<String,String>>

结果将包含

Key                    Value

              Key                   Value             
_________________________________________________

"A"             "A_1"                    "1"
                "A_2"                    "2"

"B"             "B_1"                    "1"
                "B_2"                    "2"

"C"             "C_1"                    "1"

现在我正在使用nested for loop这个.

我怎么能用LNQ或LAMBDA Expression？

Answer 1

 var result = ParentDict.GroupBy(p => p.Key[0].ToString())
                        .ToDictionary(g => g.Key, g => g.ToDictionary(x => x.Key, x => x.Value));