Here is a nice example of grouping using Linq

public void Linq40() {
int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

        var numberGroups =
            from n in numbers
            group n by n % 5 into g
            select new { Remainder = g.Key, Numbers = g };
        
        foreach (var g in numberGroups) {
            Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder);
            foreach (var n in g.Numbers) {
                Console.WriteLine(n);
            }
        }

}

more examples in C# you find : http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx[^] Hope this will help, Wim