Question

I had error from line

Dictionary<int, string> viewBusinesAndCountLeft = grptemp.Take(4).ToDictionary(x => x.Count, x => x.BusinessCategoryName);

error: “The element with the same key has already been added.”

How to do this?

var grptemp = (from adsBusines in m_adsRepository.SaleBusinesAds
               group adsBusines by adsBusines.BusinessCategory.Name
               into grp
               select new
               {
                  BusinessCategoryName = grp.Key,
                  Count = grp.Select(x => x.BusinessCategory.ChildItems.Count()).Distinct().Count()
               }).Take(8);

Dictionary<int, string> viewBusinesAndCountLeft = grptemp.Take(4).ToDictionary(x => x.Count, x => x.BusinessCategoryName);
Dictionary<int, string> viewBusinesAndCountRigth = grptemp.Skip(4).Take(4).ToDictionary(x => x.Count, x => x.BusinessCategoryName);

Answer 1

You are using the count as the key for the dictionary which means you will throw that exception whenever you happen to find two categories with the same count.

If I understand what you’re trying to do correctly, you should have the ‘business category’ as the key to the dictionary and the count as the value.

E.g.

Dictionary<string, int> viewBusinesAndCountLeft = grptemp.Take(4).ToDictionary(x => x.BusinessCategoryName, x => x.Count);