[RESOLVED] converting List to Array

[goku99]

Hello guys!

I wanted to create two lists and then convert them to arrays, with the data from this table:

idSuplier Item Price
1 Item A 10.00
1 Item B 20.00
1 Item C 30.00
2 Item A 20.00
2 Item B 30.00
2 Item C 40.00
3 Item A 30.00
3 Item B 40.00
3 Item C 50.00

Ok! the desired result would be: (1, 60.00); (2, 90.00) and (3, 120.00)

So, I've tried the following code to create my array, but I haven't any results!

Private Sub List()
        

        Dim idSupplier As List(Of Integer) = New List(Of Integer)
        Dim sumSupplier As List(Of Decimal) = New List(Of Decimal)
        Dim value As Decimal

        For i = 1 To j
            For Each col As DataGridViewRow In dgItems.Rows
                If col.Cells(0).Value = i Then
                    value = value + CDec(col.Cells(2).Value)
                    sumSupplier.Add(value)
                    idSupplier.Add(i)



                End If


            Next
            
        Next i
        Dim idSupplierArray() = idSupplier.ToArray()
        Dim sumSupplierArray() = sumSupplier.ToArray()

        
        Console.ReadLine()

    End Sub

Sorry if It seems so dumb, but its what I am...any hint?

[make me rain]

why the list should converted to array, what you are trying to do

[Lord Orwell]

assuming you actually DO have a datagrid, and any other errors aside, it looks like your logic on your for each is jacked up. You aren't resetting value to zero after each iteration for one thing, and you are adding to the new array upon each match, not after making a total. if everything else is working, you would get an array the same size as the original but with partially summed lines. your example would end up1,10;1,30;1,60; etc.
at the very least make this change:

 For i = 1 To j
      value = 0            
      For Each col As DataGridViewRow In dgItems.Rows
                If col.Cells(0).Value = i Then
                    value = value + CDec(col.Cells(2).Value)
                end if       
      next       
            sumSupplier.Add(value)
             idSupplier.Add(i)
            Next
            
        Next i

as for whether or not there are other issues, i can't say since i don't have all your project. for example i have no idea why you are doing "i = 1 to j" since you haven't assigned "j" a value anywhere.

[IanRyder]

Hi,

Here is one way you can do this using LINQ to Objects:-

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
  Dim myTableSummary = (From myRow As DataGridViewRow In DataGridView1.Rows.Cast(Of DataGridViewRow)() Where Not myRow.IsNewRow Select ID = myRow.Cells(0).Value, _
                        ItemValue = myRow.Cells(2).Value Group By ID Into G = Group, TotalItems = Count(), ValueOfItems = Sum(CDec(ItemValue)))
 
  Dim myArrayOfAnonymousTypes() = myTableSummary.ToArray
  For Each myElement In myArrayOfAnonymousTypes
    MsgBox(myElement.ID.ToString & " - " & myElement.TotalItems.ToString & " - " & myElement.ValueOfItems.ToString)
  Next
End Sub

This will create an initial Enumeration of Anonymous Types in the MyTableSummary variable but if you specifically want to convert this to an Array then you can just call the .ToArray method of the Enumeration as demonstrated above.

Hope that helps.

Cheers,

Ian

[Shaggy Hiker]

The best solution is to put a breakpoint on the outer for statement and step through the code watching what is happening. We can suggest alternatives, or sit and stare at what you did looking for a problem, but you have the code and you have the means to watch what it is doing line by line. If you haven't used the debugger before, ask about that, as it is the single most powerful tool at your disposal, and would find you the answer you seek in this, and many other, cases.

[goku99]

Hi Make me Rain!
I wish to return the sum of the Items for each idSuplier, and display which has the lowest price, highest price and the order among then. So, I was thinking in using a sorted Array, and then bring the information through labels, like: "The lowest price of the list is from "@idsuplierx@", with the amount of "@"; the highest price is from "@idspupliery@"...and the others are...
So, I want to to use a loop to put the data into two Lists: one for the supplier IDs and one for the sums of the prices, then convert each List to an array and then use Array.Sort to sort both arrays using the sums as the keys. For that I would create a List(Of Integer) for the IDs and a List(Of Decimal) for the prices. I'd then loop through the DataTable and, for each row, I'd get the index in the ID List of the current ID. If it was found then I'd add the current price to the value at the same index in the other List. If it wasn't found then I'd add the ID to one List and the price to the other. Once the loop is done, I would call the overload of Array.Sort with the two arrays as arguments. The first parameter I'd pass the price List first. I'd use a For loop to get each ID and corresponding price sum from the two arrays, which will be sorted lowest price sum to highest.

[goku99]

assuming you actually DO have a datagrid, and any other errors aside, it looks like your logic on your for each is jacked up. You aren't resetting value to zero after each iteration for one thing, and you are adding to the new array upon each match, not after making a total. if everything else is working, you would get an array the same size as the original but with partially summed lines. your example would end up1,10;1,30;1,60; etc.
at the very least make this change:

 For i = 1 To j
      value = 0            
      For Each col As DataGridViewRow In dgItems.Rows
                If col.Cells(0).Value = i Then
                    value = value + CDec(col.Cells(2).Value)
                end if       
      next       
            sumSupplier.Add(value)
             idSupplier.Add(i)
            Next
            
        Next i

as for whether or not there are other issues, i can't say since i don't have all your project. for example i have no idea why you are doing "i = 1 to j" since you haven't assigned "j" a value anywhere.

Thanks Lord! But I still cannot "cast" the results...

[goku99]

Hi,

Here is one way you can do this using LINQ to Objects:-

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
  Dim myTableSummary = (From myRow As DataGridViewRow In DataGridView1.Rows.Cast(Of DataGridViewRow)() Where Not myRow.IsNewRow Select ID = myRow.Cells(0).Value, _
                        ItemValue = myRow.Cells(2).Value Group By ID Into G = Group, TotalItems = Count(), ValueOfItems = Sum(CDec(ItemValue)))
 
  Dim myArrayOfAnonymousTypes() = myTableSummary.ToArray
  For Each myElement In myArrayOfAnonymousTypes
    MsgBox(myElement.ID.ToString & " - " & myElement.TotalItems.ToString & " - " & myElement.ValueOfItems.ToString)
  Next
End Sub

This will create an initial Enumeration of Anonymous Types in the MyTableSummary variable but if you specifically want to convert this to an Array then you can just call the .ToArray method of the Enumeration as demonstrated above.

Hope that helps.

Cheers,

Ian

Thanks Ian! It seems to work! But I still have to figure out how to display the lowest sum, the highest and the others among them.

Thanks Ian! It really worked!

[goku99]

assuming you actually DO have a datagrid, and any other errors aside, it looks like your logic on your for each is jacked up. You aren't resetting value to zero after each iteration for one thing, and you are adding to the new array upon each match, not after making a total. if everything else is working, you would get an array the same size as the original but with partially summed lines. your example would end up1,10;1,30;1,60; etc.
at the very least make this change:

 For i = 1 To j
      value = 0            
      For Each col As DataGridViewRow In dgItems.Rows
                If col.Cells(0).Value = i Then
                    value = value + CDec(col.Cells(2).Value)
                end if       
      next       
            sumSupplier.Add(value)
             idSupplier.Add(i)
            Next
            
        Next i

as for whether or not there are other issues, i can't say since i don't have all your project. for example i have no idea why you are doing "i = 1 to j" since you haven't assigned "j" a value anywhere.

Lord, j represents the number of suppliers...

[IanRyder]

Hi,

You can use MIN and MAX functions in the LINQ query to get the Minimum and Maximum value for each group. i.e:-

MaxValue = Max(CDec(ItemValue)), MinValue = Min(CDec(ItemValue))

As to other calculations you need doing, these all need to be Aggregate functions due to the fact that you are working within Groups of Items.

Hope that helps.

Cheers,

Ian

[goku99]

Hi,

You can use MIN and MAX functions in the LINQ query to get the Minimum and Maximum value for each group. i.e:-

MaxValue = Max(CDec(ItemValue)), MinValue = Min(CDec(ItemValue))

As to other calculations you need doing, these all need to be Aggregate functions due to the fact that you are working within Groups of Items.

Hope that helps.

Cheers,

Ian

Hi, thanks again! Sorry being a dumb, but although you have given me tips, when I implemented your code, I got the error message:
"InvalidCastExceptions was unhandled
Conversion from string " & myElement.MaxValue.ToString &" to type 'Double' is not valid."

Here is the code:

Dim myTableSummary = (From myRow As DataGridViewRow In dgItensPesquisado.Rows.Cast(Of DataGridViewRow)() Where Not myRow.IsNewRow Select ID = myRow.Cells(0).Value, _
                        ItemValue = myRow.Cells(2).Value Group By ID Into G = Group, TotalItems = Count(), ValueOfItems = Sum(CDec(ItemValue)), MaxValue = Max(CDec(ItemValue)), MinValue = Min(CDec(ItemValue)))

        Dim myArrayOfAnonymousTypes() = myTableSummary.ToArray
        For Each myElement In myArrayOfAnonymousTypes
            MsgBox(myElement.ID.ToString & " - " & myElement.TotalItems.ToString & " - " & myElement.ValueOfItems.ToString - " & myElement.MaxValue.ToString & ")

            
        Next

[IanRyder]

Hi,

You have got the structure of the message incorrect. You are actually trying to do math calculations with strings as you have it now. It should say this:-

MsgBox(myElement.ID.ToString & " - " & myElement.TotalItems.ToString & " - " & myElement.ValueOfItems.ToString & " - " & myElement.MaxValue.ToString)

Hope that helps.

Cheers,

Ian

[goku99]

Hey, Thanks again! Topic closed! Thanks a lot!