[RESOLVED] LINQ Problem

[Jenner]

I got a class object that holds some data: Customer, State, Sales, Date. I then call a database with a large collection of data and populate several thousand of these class objects.

Next, using a little LINQ, I make two IEnumerable collections of these objects based on the date-range.

Each of these, I use some more LINQ to Aggregate them into Groups by State and Customer. Thus, now I got two lists, each list has a unique identity based on State and Customer.

How do I get a list of all items that are in List2 that don't have a matching entry in List1 (matching based on the State/Customer)? I cobbled together a way to do it but I suspect there's a far simpler solution. Also, looking over this code, can anything be simplified? This is my first time doing mass-LINQ manipulation of data objects. I usually don't get this detailed in it.

Code is below for review.

        Dim r1 = From so In Me Where so.DateInvoiced >= dteFrom1 AndAlso so.DateInvoiced <= dteTo1 Select so
        Dim r2 = From so In Me Where so.DateInvoiced >= dteFrom2 AndAlso so.DateInvoiced <= dteTo2 Select so

        Dim rUSA1 = From so In r1 Where Not so.Ship_State.Equals(String.Empty) Select so
        Dim rUSA2 = From so In r2 Where Not so.Ship_State.Equals(String.Empty) Select so

        Dim decGrandTotal1 As Decimal = Aggregate so In r1 Select so.Total Into Sum()
        Dim decGrandTotal2 As Decimal = Aggregate so In r2 Select so.Total Into Sum()

        Dim rStates1 = From so In rUSA1 Group so By so.Ship_State, so.CustomerCode Into Group Select Ship_State, CustomerCode, Total = Group.Sum(Function(so) so.Total), Percent = Group.Sum(Function(so) so.Total) / decGrandTotal1
        Dim rStates2 = From so In rUSA2 Group so By so.Ship_State, so.CustomerCode Into Group Select Ship_State, CustomerCode, Total = Group.Sum(Function(so) so.Total), Percent = Group.Sum(Function(so) so.Total) / decGrandTotal2

        'How do I get a list of all rStates2 items that don't have a matching rStates1 record?
        'Can any of the above code be simplified (such as the Total = Group.Sum(Function) parts)?