Error code using Linq to add to a variable - vb.net

Question

I'll start with the problem, and then describe how the procedure works.
I'm getting a an error saying:
Value of type 'System.Collections.Generic.IEnumerable(Of LunchMoneyGame.LunchMoneyMainForm.Group)' cannot be converted to 'LunchMoneyGame.LunchMoneyMainForm.Group'.
The blue underline pinpointing the problem is on Dim obj As LunchMoneyGame.LunchMoneyMainForm.Group = From r In temp Where r.ID = Number Select r on the right side of the operator.
I know it is something to do with explicitness
--
This is for a table top card game i am converting to a text game.
The goal of this sub procedure is to subtract a card from a players hand and add it to the discard pile. Once added to the discard pile I then call the discard pile to move the cards from the discard pile to the card deck.
The problem starts with the number generator.
What I'm doing is randomly picking a card from the deck. by generating a the card id of a card in the deck. Once the ID is generated using linq the number generated then takes a card, then adds the card to the players inventory (quantity integer), and subtracts from the deck.
T represents whose turn it is. Currently for testing purposes I have coded it for only 2 players in terms of the T variable.
Private Sub GrabFromDeckAndDiscard()
Dim CardCheckBoxInteger As Integer
'ReDeclare CheckBox Array for Private sub
Dim CardCheckBoxArray() As CheckBox = {CardCheckBox1, CardCheckBox2, CardCheckBox3, CardCheckBox4, CardCheckBox5}
'Discard
Select Case T
Case 0
Player1HandGroup(NumberArray(Checks)).QuantityInteger -= 1
Case 1
Player1HandGroup(NumberArray(Checks)).QuantityInteger2 -= 1
Case 2
Player1HandGroup(NumberArray(Checks)).QuantityInteger3 -= 1
Case 3
Player1HandGroup(NumberArray(Checks)).QuantityInteger4 -= 1
Case 4
Player1HandGroup(NumberArray(Checks)).QuantityInteger5 -= 1
End Select
'Add Card to Discard Pile
DiscardGroup(NumberArray(Checks)).QuantityInteger += 1
'Shuffle Deck from Discard Pile if Deck is out of cards
Call DiscardPile()
'Reset Number Generator, unless weapon isn't discard
Dim temp As IEnumerable(Of LunchMoneyGame.LunchMoneyMainForm.Group) = From r In DeckGroup Where r.QuantityInteger > 0 Select r
If temp IsNot Nothing AndAlso temp.count > 0 Then
Number = (temp(Rnd.Next(0, temp.Count)).ID)
' ** Edit **: This will give you the actual object to be manipulated
Dim obj As LunchMoneyGame.LunchMoneyMainForm.Group = (From r In temp Where r.ID = Number Select r).Single
Dim PlayerQuantitySubtractionInteger As Integer
For PlayerQuantitySubtractionInteger = ChecksDynamicA To ChecksDynamicB
' ** Edit **
obj.QuantityInteger -= 1
'Select the Player depending value of T
Select Case T
Case 0
Player1HandGroup(Number).QuantityInteger += 1
Case 1
Player1HandGroup(Number).QuantityInteger2 += 1
Case 2
Player1HandGroup(Number).QuantityInteger3 += 1
Case 3
Player1HandGroup(Number).QuantityInteger4 += 1
Case 4
Player1HandGroup(Number).QuantityInteger5 += 1
End Select
CardTypeArray(PlayerQuantitySubtractionInteger) = Player1HandGroup(Number).CardType
CardCheckBoxArray(TextBoxInteger).Text = Player1HandGroup(Number).CardNameString
NumberArray(PlayerQuantitySubtractionInteger) = Number
Next PlayerQuantitySubtractionInteger
End If
'Switch to next player
Select Case T
Case 0
For CardCheckBoxInteger = 0 To 4
CardCheckBoxArray(CardCheckBoxInteger).Text = Player1HandGroup(NumberArray(CardCheckBoxInteger + 5)).CardNameString
Next
T += 1
Case 1
If GameSize = 2 Then
For CardCheckBoxInteger = 0 To 4
CardCheckBoxArray(CardCheckBoxInteger).Text = Player1HandGroup(NumberArray(CardCheckBoxInteger)).CardNameString
Next CardCheckBoxInteger
T -= 1
End If
If GameSize > 2 Then
T += 1
End If
Case 2
Case 3
Case 4
End Select
Label1.Text = T.ToString
'Clear Check Boxes when turn is finished
For CardCheckBoxInteger = 0 To 4
CardCheckBoxArray(CardCheckBoxInteger).Checked = False
Next
'Turn off play button
PlayButton.Enabled = False
End Sub

Answer 1

From r In temp
Where r.ID = Number
Select r
Returns a collection of everything which matches the Where clause (see this for the MSDN documentation). .NET represents this as an IEnumerable, which means a collection of things which can be iterated over (e.g. using a For loop or something like that).
There is no automatic concept that you'll only get one record returned even though your condition is an = (there may also be conditions, broadly, where no elements are returned such as when nothing matches the equality condition or where multiple things match the equality condition).
In order to indicate that you only want one element you can use the First, Single, FirstOrDefault or SingleOrDefault methods.
For example:
Dim obj As LunchMoneyGame.LunchMoneyMainForm.Group = (From r In temp Where r.ID = Number Select r).Single()
Which will give you an object of type LunchMoneyGame.LunchMoneyMainForm.Group, which I think you're looking for in this case.
As an aside, it's not bad to know the difference between the methods I've outlined above. In my lay perspective (as I'm no expert):
First returns the first item in the collection or throws an Exception if the collection is empty
FirstOrDefault returns the first item in the collection or null if empty
Single returns the only item in the collection or throws an Exception if the collection does not have exactly one item
SingleOrDefault returns the first item in the collection, null if the collection is empty and throws an exception if the collection has more than 1 element
So in your case, since you should only match on a single item with the = condition I would suggest using Single or SingleOrDefault
PS. Sorry, when I say null above, that'll be Nothing in VB.NET speak