public class ItemList
{
    public int GuID { get; set; }
    public int ItemID { get; set; }
    public string Name { get; set; }
    public entityType Status { get; set; }

    public class Waypoint
    {
        public int Zone { get; set; }
        public int SubID { get; set; }
        public int Heading { get; set; }
        public float PosX { get; set; }
        public float PosY { get; set; }
        public float PosZ { get; set; }
    }
    public List<Waypoint> Routes = new List<Waypoint>();
}

I have a list of items using the above class and now I need to group it by ItemID and join the first entry of Routes of each iqual ItemID.

So for example, let's say on my list I have:

GUID    ItemID    ListOfRoutes
   1        23    first entry only
   2        23    first entry only
   3        23    first entry only
   4        23    first entry only
   5        23    first entry only
   6        23    first entry only
   7        23    first entry only

Means I have to group entries 1 to 7 as 1 Item with all the Routes entries.

So I would have one ItemID 23 with 7 Routes on it where those routes are the first element of that given GUID Routes List.

My question is if it is possible using LINQ to make a statment to do something like that this:

var query = from ItemList entry in myList
            where status.Contains(entry.Status)
            group entry by entry.ItemID into result
            select new
            {
                items = new
                {
                    ID = entry.ItemID,
                    Name = entry.Name
                },

                routes = from ItemList m in entry
                group m.Routes.FirstOrDefault() by n.NpcID into m2
            };

So basicly I would have list of unique IDS information with a inner list of all the first entry of each GUID route that had the same ItemID.

<<< UPDATE: >>>

This would be an example of public List<ItemList> myList = new List<ItemList>(); data:

GUID    ItemID      ListOfRoutes
   1        20         Routes[1]
   2        20         Routes[2]
   3        20         Routes[3]
   4        20         Routes[4]
   5        20         Routes[5]
   6        55         Routes[6]
   7        55         Routes[7]
   8        55         Routes[8]
   9         1         Routes[9]
  10         1        Routes[10]

As you can see GUID is unique, ItemID can reapeat it self. Each GUID has a Routes list and all routes list have a minimum of 1 entry and above.

Routes example.

Routes[1] have:

Entry   Zone    SubID   Heading     PosX    PosY    PosZ
    1   1200        0       100     1029.32 837.21  29.10
    2   1200        0       120     1129.32 537.21  29.10
    3   1200        0       180     1229.32 137.21  29.10
    4   1200        0       360     1329.32 437.21  29.10
    5   1200        0       100     1429.32 637.21  29.10

Routes[2] have:

Entry   Zone    SubID   Heading     PosX    PosY    PosZ
    1    100        0       10      129.32  437.21  29.10

So what I want to do is a list of all entries I have on myList grouped by ItemID maintainning the fields ItemID and Name ... and a new field or item that will have all the first elements of Routes of those GUIDs.

For example ItemID 20 would produce the follow result:

ItemID, Name, ListOfRoutes

This ItemID ListOfRoutes would contain

Routes[1] first entry:

Entry   Zone    SubID   Heading     PosX    PosY    PosZ
    1   1200        0       100     1029.32 837.21  29.10

Routes[2] first entry:

Entry   Zone    SubID   Heading     PosX    PosY    PosZ
    1    100        0       10      129.32  437.21  29.10

Routes[3], Routes[4], Routes[5] first entries.

Example of how myList is feeded:

ItemList newItem = new ItemList();
newItem.GUID = GUID;
newItem.ItemID = ItemID;
newItem.Name = Name;
newItem.Status = Status;
// Item location
ItemList.Waypoint itemLocation = new ItemList.Waypoint();
itemLocation.SubID = SubID;
itemLocation.Zone = Zone;
itemLocation.Heading = convertHeading(Heading);
itemLocation.PosX = PosX;
itemLocation.PosY = PosY;
itemLocation.PosZ = PosZ;
itemLocation.Rest = Rest;
newItem.Routes.Add(itemLocation);
myList.Add(newItem);