grouping in LINQ query - vb.net

Question

Given a table of thousands of rows of data as shown in the sample below
Id Date SymbolId NumOccs HighProjection LowProjection ProjectionTypeId
1 2014-04-09 28 45 1.0765 1.0519 1
2 2014-04-10 5 44 60.23 58.03 1
3 2014-04-11 29 77 1.026 1.0153 1
and a Class defined as
Public Class ProjectionPerformance
Public symbolId As Integer
Public Name as String
Public Date as String
Public ActualRange as Decimal
End Class
I am trying to return the following for each symbolId;
The symbolId (from this table)
The symbol Name (from the symbols table)
The Actual Range (High Projection - Low Projection)
Can this be done in one query since i am essentially in need of a Dictionary(Of Integer, List(Of ProjectionPerformance)) where the integer is the symbolId and the List is generated from the query?
Updated:
So as to be a little clearer, Here is what I'm doing so far but contains two LINQ iterations
Public Shared Function GetRangeProjectionPerformance(Optional daysToRetrieve As Integer = 100) As Dictionary(Of Integer, List(Of ProjectionPerformance))
Dim todaysDate As Date = DateTime.Now.Date
Dim lookbackDate As Date = todaysDate.AddDays(daysToRetrieve * -1)
Dim temp As New Dictionary(Of Integer, List(Of ProjectionPerformance))
Using ctx As New ProjectionsEntities()
Dim query = (From d In ctx.projections
Where d.SymbolId <= 42 AndAlso d.Date >= lookbackDate
Join t In ctx.symbols On d.SymbolId Equals t.Id
Let actualRange = d.HighProjection - d.LowProjection
Select New With {
d.Date,
d.SymbolId,
t.Name,
actualRange}).GroupBy(Function(o) o.SymbolId).ToDictionary(Function(p) p.Key)
For Each itm In query
Dim rpp As New ProjectionPerformance
Dim rppList As New List(Of ProjectionPerformance)
If itm.Value.Count > 0 Then
For x As Integer = 0 To itm.Value.Count - 1
Dim bb As Integer = Convert.ToInt32(itm.Value(x).SymbolId)
With rpp
.SymbolId = bb
.ProjectionDate = itm.Value(x).Date.ToString()
.Name = itm.Value(x).Name
.ProjectedRange = itm.Value(x).actualRange
End With
rppList.Add(rpp)
Next
End If
temp.Add(itm.Key, rppList)
Next
End Using
Return temp
End Function

Answer 1

I'm going to answer in C#, but I think you'll get the gist of it anyway. Basically, you can group by SymbolId, build your object graph and then use ToDictionary using the Key to create dictionary.
var result = (From d In _projectionEntities.projections
Where d.SymbolId <= 42
group d by d.SymbolId into g
select new {
SymbolId = g.Key,
ProjectionPerformances =
g.Select(gg=>new ProjectionPerformance{
SymbolId = gg.SymbolId,
Name = gg.Symbol.Name,
rpDate = gg.Date.ToString(),
ActualRange = gg.HighProjection - gg.LowProjection
})
.ToDictionary(g=>g.SymbolId);

Answer 2

Try
Dim Result = (From d In _ProjectionEntities.projections
Join t In _projectionEntities.symbols On d.SymbolId Equals t.Id
Where d.SymbolId <= 42
Select New With {.SymbolID = d.SymbolID
.Date = d.Date
.Name = t.Name
.ActualRange = d.HighProjection - d.LowProjection})