how to get unique value in LINQ code example

Example 1: c# linq select only unique values from list

var uniq = allvalues.GroupBy(x => x.Id).Select(y=>y.First()).Distinct();

Example 2: c# linq select only unique values from list

var uniqueCategories =  repository.GetAllProducts()
                                  .Select(p=>p.Category)
                                  .Distinct();