Linq on nested Dictionary

Question

I have a dictionary of dictionary and I want to find a value from inner dictionary by Linq .

My code is:

private Dictionary<string, Dictionary<int, string>> SubCategoryDictionary = new Dictionary<string, Dictionary<int, string>>();
  private Dictionary<int, string> BGA_Dictionary = new Dictionary<int, string>();
  private Dictionary<int, string> Lead3D_Dictionary = new Dictionary<int, string>();
  private Dictionary<int, string> Lead2D_Dictionary = new Dictionary<int, string>();
  private Dictionary<int, string> Leadless_Dictionary = new Dictionary<int, string>();
  private Dictionary<int, string> PIC_Dictionary = new Dictionary<int, string>();

In my constructor I have all values like this:--

BGA_Dictionary.Add(1, "Body_Measurement");
     BGA_Dictionary.Add(2, "Ball_Measurement");
     SubCategoryDictionary.Add("BGA", BGA_Dictionary);

     Lead3D_Dictionary.Add(1, "Component_Height");
     Lead3D_Dictionary.Add(2, "Rib_Measurement");
     SubCategoryDictionary.Add("Package", Lead3D_Dictionary);

     Lead2D_Dictionary.Add(1, "Dirt_Inspection");
     Lead2D_Dictionary.Add(2, "Half_Cut_Inspection");
     SubCategoryDictionary.Add("Mark", Lead2D_Dictionary);

Now I need a Lambda expression which will give me something like : when key of SubCategoryDictionary ="Mark" and key of Lead3D_Dictionary =2 then I should get "Rib_Measurement".

I tried with following code :

string q = (from cls in SubCategoryDictionary
                 from s in cls.Value
                 where cls.Key == "Mark" && s.Key == 3
                 select s.Value).FirstOrDefault();


foreach (var a in q)
     {

     }

This above code works but I need in lambda expression. So if someone help me in formation of Lambda formation. It will be of great help.

Thanks.

Answer 1

I'm not sure why you ever need a lambda for accessing a dictionary by keys, but here it is:

Func<string,int,string> lambda = (k1, k2) => SubCategoryDictionary[k1][k2];

Now you can invoke it with var subCategory = lambda("Mark", 2);

Answer 2

I guess below code should get you the value you are trying to get.

        var lead3 = SubCategoryDictionary["Mark"].SingleOrDefault(x => x.Key == 2).Value;

The idea is to use the Key of the first dictionary and get the value of it than filter it with SingleOrDefault method by providing a key to the inner dictionary value you are interested in.

Hope this helps