How to get the unification of the keys set of dictionaries?

Question

Hi,

 I have a List of Dictionaries and I need to merge them according to their keys , i.e , if I have the following two dictionaries:

KEY, VALUE

18,0

19,1

15,2

13,3

===

19,0

12,1

13,2

14,3

===

So, I need to get the following result;

18,0

19,1

15,2

13,3

12,4

14,5

I have used the following statement:

unified_ht = unified_ht.Union(pageIDs_Hashtables_List[ht]).GroupBy(a => a.Key).ToDictionary(a => a.Key, a => a.First().Value);

and got the following result:

18,0

19,1

15,2

13,3

12,1

14,3

So, how to correct my result?

thanks so much in advance,

Regards,

Aya.

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Aya Zoghby