Question

i’ve three Dictonaries like

Dictionary<int,List<string>> D1 = new Dictionary<int,List<string>>(); 
Dictionary<int,List<string>> D2= new Dictionary<int,List<string>>(); 
Dictionary<int,List<string>> D3 new Dictionary<int,List<string>>(); 


D1[1] = new List<string>{"a","b"}; 
D1[2] = new List<string>{"c","d"}; 
D1[3] = new List<string>{"e","f"}; 
D1[4] = new List<string>{"h"}; 

D2[1] = new List<string>{"a","b"}; 
D2[2] = new List<string>{"c","d"}; 
D2[3] = new List<string>{"e","f"}; 
D2[4] = new List<string>{"g"}; 
D2[5] = new List<string>{"b","h"}; 
D2[6] = new List<string>{"f","l"}; 
D2[7] = new List<string>{"z"}; 

i need to merge the two dictonary into a single dictonary

like

D3[1] = {"a","b","h"} 
D3[2] = {"c","d"} 
D3[3] = {"e","f","l"} 

Merging Rule:

D1[1]={“a”,”b”} this list will be compared with the values in the D2

D2[1]={“a”,”b”}

D2[5]={“b”,”h”}

so the above three will be merged into

D3[1]={“a”,”b”,”h”}

is there any idea to do this using LINQ

Answer 1

However are you trying to merge the values, you will probably want to use one of these options:

D3[1] = D1[1].Union(D2[1]);

or

D3[1] = D1[1].Concat(D2[1]);

Edit – an ugly-looking method for joined merges Linq-style:

foreach (var kvp in D1)
{
    D3[kvp.Key] =
        (from string letter in kvp.Value
        select
            (from IEnumerable<string> list in D2.Values
            where list.Contains(letter)
            select list)
             // Union all the D2 lists containing a letter from D1.
            .Aggregate((aggregated, next) => aggregated.Union(next)))
        // Union all the D2 lists containing all the letter from D1.
        .Aggregate((aggregated, next) => aggregated.Union(next))
        // Convert the unioned letters to a List.
        .ToList();
}

The code keeps the lists in D2, it would be pretty easy to modify the code to remove the matched lists from D2.