In the following linq query I have a division by zero exception wich I can't seem to code around. It occurs when the Sum of fldDevider returns 0.
Dim lstToReturn As List(Of MonthData)
lstToReturn = (
From myRow In dtSpotData.AsEnumerable()
Group myRow By myRow.Field(Of DateTime)(fldstartdate).Month Into Group
Select New MonthData() With {
.Month = Month,
.ValuePerMonth =
(
Group.Sum(Function(dr) dr.Field(Of [Decimal])(fldSomeGeneralValue)) /
(
Group.Sum(Function(dr) CDec(dr.Field(Of String)(fldDevider)))
)
)
}
).ToList()
How can I Make sure the ValuePerMonth field is 0 when the Group.Sum(Function(dr) CDec(dr.Field(Of String)(fldDevider))) function returns a 0. Or how do I return a 1 for Sum fldDevider if it is actually 0.
Some tips on how to do better conversions from string to decimal are welcome too.
I am used to C# syntax but I would use a 'let' to capture the value of the dividing number and only use it if it is greater than zero, and otherwise use 1.
Dim lstToReturn As List(Of MonthData)
lstToReturn = (
From myRow In dtSpotData.AsEnumerable()
Group myRow By myRow.Field(Of DateTime)(fldstartdate).Month Into Group
Let div = Group.Sum(Function(dr) CDec(dr.Field(Of String)(fldDevider)))
Select New MonthData() With {
.Month = Month,
.ValuePerMonth =
(
Group.Sum(Function(dr) dr.Field(Of [Decimal])(fldSomeGeneralValue)) / If(div > 0, div, 1)
)
}
).ToList()
Related
I am trying to make a quick sort however i am having trouble with a stack overflow exception in VB.net.
The sort works correctly when x = 3, intermittently when x = 5 and on one occasion sorted half of the list when x = 10.
Please advise, thanks
Dim x As Integer = 10
Dim numArrray(x - 1) As Integer
For i = 0 To x - 1
Randomize()
numArrray(i) = CInt(Rnd() * 9)
Next
Quicksort(numArrray, 0, numArrray.Length - 1)
For i = 0 To x - 1
Console.Write(numArrray(i))
Next
Console.ReadLine()
End Sub
Sub Quicksort(ByVal array() As Integer, ByVal min As Integer, ByVal max As Integer)
Dim pivot As Integer
If min < max Then
pivot = partition(array, min, max)
Quicksort(array, min, pivot - 1)
Quicksort(array, pivot + 1, max)
End If
End Sub
Function partition(ByVal array() As Integer, ByVal min As Integer, ByVal max As Integer) As Integer
Dim pivot As Integer = array(max)
Dim count As Integer = min - 1
Dim placeholder As Integer
For i = min To max - 1
If array(i) < pivot Then
count += 1
placeholder = array(count)
array(count) = array(i)
array(i) = placeholder
End If
Next
If array(max) < array(count + 1) Then
placeholder = array(count + 1)
array(count + 1) = array(max)
array(max) = placeholder
End If
Return count
End Function
Since its a stack overflow it will be in the nested calls to Quicksort, looking at partition I think you have a bounds error, as per this version of the algorithm en.wikipedia.org/wiki/Quicksort you should return count + 1 from partition, on your current implementation count can start below min and stay that way which would be an infinite regression as your nested call would have the same inputs (ie if you return count = min - 1 then you do a recursive call back to Quicksort(array, pivot + 1, max) == Quicksort(array, min, max)
I'm trying to calculate how many layers a commodity will be stacked in. I have a variable quantity (iQty), a given width for the loadbed (dRTW), a width per unit for the commodity (dWidth) and a quantity per layer (iLayerQty).
The quantity per layer is calculated as iLayerQty = Int(dRTW/dWidth)
Now I need to divide the total quantity by the quantity per layer and round up. In an Excel formula it would be easy, but I'm trying to avoid WorksheetFunction calls to minimise A1/R1C1 confusion. At the moment I'm approximating it with this:
(Number of layers) = ((Int(iQty / iLayerQty) + 1)
And that works fine most of the time - except when the numbers give an integer (a cargo width of 0.5 m, for instance, fitting onto a 2.5 m rolltrailer). In those instances, of course, adding the one ruins the result.
Is there any handy way of tweaking that formula to get a better upward rounding?
I don't see any reason to avoid WorksheetFunction; I don't see any confusion here.
Number_of_layers = WorksheetFunction.RoundUp(iQty / iLayerQty, 0)
You could also roll your own function:
Function RoundUp(ByVal Value As Double)
If Int(Value) = Value Then
RoundUp = Value
Else
RoundUp = Int(Value) + 1
End If
End Function
Call it like this:
Number_of_layers = RoundUp(iQty / iLayerQty)
If using a WorksheetFunction object to access a ROUNDUP or CEILING function is off the table then the same can be accomplished with some maths.
Number of layers = Int(iQty / iLayerQty) - CBool(Int(iQty / iLayerQty) <> Round(iQty / iLayerQty, 14))
A VBA True is the equivalent of (-1) when used mathematically. The VBA Round is there to avoid 15 digit floating point errors.
I use -int(-x) to get the ceiling.
?-int(-1.1) ' get ceil(1.1)
2
?-int(1.1) ' get ceil(-1.1)
-1
?-int(-5) ' get ceil(5)
5
These are the functions I put together for this purpose.
Function RoundUp(ByVal value As Double) as Integer
Dim intVal As Integer
Dim delta As Double
intVal = CInt(value)
delta = intVal - value
If delta < 0 Then
RoundUp = intVal + 1
Else
RoundUp = intVal
End If
End Function
Function RoundDown(ByVal value As Double) as Integer
Dim intVal As Integer
Dim delta As Double
intVal = CInt(value)
delta = intVal - value
If delta <= 0 Then
RoundDown = intVal
ElseIf delta > 0 Then
RoundDown = intVal - 1
End If
End Function
This is my Ceiling in VBA.
Function Ceiling(ByVal Number As Double, ByVal Significance As Double) As Double
Dim intVal As Long
Dim delta As Double
Dim RoundValue As Double
Dim PreReturn As Double
If Significance = 0 Then
RoundValue = 1
Else
RoundValue = 1 / Significance
End If
Number = Number * RoundValue
intVal = CLng(Number)
delta = intVal - Number
If delta < 0 Then
PreReturn = intVal + 1
Else
PreReturn = intVal
End If
Ceiling = PreReturn / RoundValue
End Function
I have the follow custom function that I am using in an SSRS report in order to calculate an average value using the LookUpSet function. I have a number of results in the set that are returned that are null. At the moment this function is taking these as 0 and increasing the count. How would I modify this to exclude the 0 values so that it just skips them and keeps the count the same. ie. just excludes them completely from the dataset that is returned?
Function AvgLookup(ByVal items As Object()) As Decimal
If items Is Nothing Then
Return Nothing
End If
Dim suma As Decimal = New Decimal()
Dim ct as Integer = New Integer()
Dim Avg as Decimal = New Decimal()
suma = 0
ct = 0
For Each item As Object In items
suma += Convert.ToDecimal(item)
ct += 1
Next
Avg = suma / ct
If (ct = 0) Then return 0 else return Avg
End Function
It seems the easiest way would be to add a IF statement in your loop. This assumes it is converting the NULLS to 0 and you have no 0 values you want.
For Each item As Object In items
IF Convert.ToDecimal(item) <> 0
suma += Convert.ToDecimal(item)
ct += 1
ENDIF
Next
How do I perform group in LINQ inside vb code (dot.net v4.0) with DataTable and sum on the group?
In the sample below I need to add group by GroupName, ProductName and perform sum on QTY. The columns, order and where should remain as in sample, I just need to add the group and sum. The format should remain the same (getting row using e("FieldName")).
Dim ordersTable As DataTable = _dsProd.Tables("tblProductSummary")
Dim query =
(From e In ordersTable
Where (e("Type").ToString() = "1" Or IsDBNull(e("Type")))
Order By e("GroupSortOrder") Ascending, e("ProductName")
Select
GroupName = e("GroupName"),
ProductName = e("ProductName"),
QTY = e("QTY"),
Type= e("Type")
)
Dim query =
(From e In ordersTable
Where (e("Type").ToString() = "1" Or IsDBNull(e("Type")))
Order By e("GroupSortOrder") Ascending, e("ProductName")
Group e By Key = New With {
.ProductName = e("ProductName"),
.GroupName = e("GroupName")
} Into Group
Select New With {
.ProductName = Key.ProductName,
.GroupName = Key.GroupName,
.Sum = Group.Sum(Function(x) x("QTY"))
})
I've the following Datatable:
[Date];[Time];[ProcessID];[ID]
24.09.2012;08:18:00;4000;1
24.09.2012;08:18:00;4000;2
24.09.2012;08:19:00;4001;3
24.09.2012;08:23:00;4002;4
24.09.2012;08:32:00;4003;5
...
As result I would like to have a grouping by a 15-minute Time-Interval to count the ProcessID´s:
[Interval];[ProcessID Count]
8:15:00 - 8:29:00;3
8:30:00 - 8:45:00;1
How to achieve this goal?
Here's the solution against Linq-to-SQL (on SQL Server) with the DateTime being in a single field (a LINQpad query):
Const BaseDate As Date = #9/24/2012#
Const PeriodMinutes As Integer = 15
Dim p = From t In TestData _
Group By q=CInt(Math.Floor((t.SomeDate - BaseDate).TotalMinutes/PeriodMinutes)) Into Group _
Select s=BaseDate.AddMinutes(q*PeriodMinutes), _
e=BaseDate.AddMinutes((q+1)*PeriodMinutes), _
ids=Aggregate g In Group Select g.ProcessID Distinct Into Count()
p.Dump
Using different types and other "little" adjustments could produce simpler SQL backend code.
For your actual database, you need to adjust the Group By, although it now depends upon what your Time column is converted to through Linq-to-SQL and/or your database's driver.
As it is a TimeSpan the Group By becomes something like:
Group By d=t.[Date], q=CInt(Math.Floor(t.[Time].TotalMinutes/PeriodMinutes)) Into Group _
Select s=d.AddMinutes(q*PeriodMinutes), _
e=d.AddMinutes((q+1)*PeriodMinutes), _
ids=Aggregate g In Group Select g.ProcessID Distinct Into Count()
This should work (however, not tested):
Dim groupedByQuarter =
From r In table
Let day = r.Field(Of Date)("Date").Date
Let time = r.Field(Of TimeSpan)("Time")
Let quarter = time.Add(TimeSpan.FromMinutes((-1) * time.Minutes Mod 15))
Group r By Key = New With {Key .day = day, Key .quarter = quarter} Into TimeGroup = Group
Select New With {
.Interval = String.Format("{0} - {1}",
Key.quarter,
Key.quarter.Add(TimeSpan.FromMinutes(14))),
.ProcessCount = TimeGroup.Select(Function(r) r.Field(Of Int32)("ProcessID")).Distinct().Count()
}