Import data from excel and consolidate - vb.net

Question

I'm using the below code to read from an excel file and add certain columns into a listview. Once imported i'm then exporting them to a CSV (code not shown).
My problem is that the excel file is a till extract and it displays the data by transaction which results in thousands of lines. I would like to perform the excel equivalent of SUMIF based on the EPoS line and consolidate the info if thats possible?
Sample of data below...
Public Structure ExcelRows
Dim Unit As String
Dim Outlet As String
Dim EPoS As String
Dim Quantity As String
Dim Value As String
Dim DateSale As String
End Structure
Public ExcelRowList As List(Of ExcelRows) = New List(Of ExcelRows)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Public Function GetInfo() As Boolean
Dim Completed As Boolean = False
Dim MyExcel As New Excel.Application
Dim enUK As New CultureInfo("en-GB")
Dim DOS As String = "01/04/15"
MyExcel.Workbooks.Open("C:\Dropbox\Tills\taRunAction1.xlsx")
MyExcel.Sheets("Report").Activate()
MyExcel.Range("A10").Activate()
Dim ThisRow As New ExcelRows
Do
If MyExcel.ActiveCell.Value > Nothing Or MyExcel.ActiveCell.Text > Nothing Then
ThisRow.Unit = MyExcel.ActiveCell.Value
MyExcel.ActiveCell.Offset(0, 1).Activate()
ThisRow.Outlet = MyExcel.ActiveCell.Value
MyExcel.ActiveCell.Offset(0, 1).Activate()
ThisRow.DateSale = MyExcel.ActiveCell.Value
MyExcel.ActiveCell.Offset(0, 2).Activate()
ThisRow.EPoS = MyExcel.ActiveCell.Value
MyExcel.ActiveCell.Offset(0, 1).Activate()
ThisRow.Quantity = MyExcel.ActiveCell.Value
MyExcel.ActiveCell.Offset(0, 1).Activate()
ThisRow.Value = MyExcel.ActiveCell.Value
ExcelRowList.Add(ThisRow)
MyExcel.ActiveCell.Offset(1, -6).Activate()
Else
Completed = True
Exit Do
End If
Loop
MyExcel.Workbooks.Close()
MyExcel = Nothing
Return Completed
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If GetInfo() = True Then
For Each xItem In ExcelRowList
Dim lViewItem As ListViewItem
lViewItem = ListView1.Items.Add(xItem.Unit)
lViewItem.SubItems.AddRange(New String() {xItem.Outlet, xItem.EPoS, xItem.Quantity, xItem.Value, xItem.DateSale})
Next
End If
End Sub

Answer 1

#Plutonix's answer is a good idea and I totally agree with his comments about changing your ExcelRows structure/class fields from strings to the appropriate numerical type.
Another possibility is to use LINQ to group the data from your ExcelRowList. Something like the following
Dim results = From r In ExcelRowList
Group By r.EPoS
Into Group, Sum(r.Value * r.Quantity)
Note that this won't work as is because r.Value and r.Quantity are strings so you can't multiply them. So you should change the field types in your structure and then when you are looping through the cells, cast the cell value to the correct type. You will have to decide what to do if the cast fails.
Group By on MSDN.

Answer 2

One way to do this would be to use a DataTable:
Private dt As DataTable
...
dt = New DataTable
dt.Columns.Add("EPOS", GetType(Integer))
dt.Columns.Add("Unit", GetType(String))
dt.Columns.Add("Quantity", GetType(Integer))
dt.Columns.Add("Value", GetType(Decimal))
dt.Columns.Add("Total", GetType(Decimal))
dt.Columns.Add("Date", GetType(DateTime))
Dim keys As DataColumn() = {dt.Columns("EPOS")}
dt.PrimaryKey = keys
It is not clear whether "VALUE" is the Unit Price or Sale Amount because all the units are 1. I am not sure I would repeat data such as the SaleDate over and over, The key is that the DataTable could replace the XLRows Structure.
One key is that you want to work with properly Typed data so you can multiply and add. The XLRow structure is not properly typed - everything is string rather than Date, Decimal, Integer etc.
A. XLRow Class to Convert
For this, convert the XLRow structure to a class. Its role would be to take in string data from XL and convert to Typed data. Next, the DataTable is used to collect the rollup data.
For this, the PrimaryKey definition above is critical. It will prevent you from adding a second (or 1000th) "Pepsi" item and allow you to find that summary item. Perhaps best of all, you can get rid of the ListView and use a DataGridView:
dgv.DataSource = dt
With one line of code, the DGV will create the columns and display all the rows in the DataTable. Unlike a ListView it will update itself as the underlying data in the DataTable changes. To iterate your data to summarize inside a loop:
' get the row for this EPOS code
Dim dr As DataRow = dt.Rows.Find(xl.EPOS)
If dr IsNot Nothing Then
' we already have this item, increment Quan, TotalSales:
dr("Quantity") += xl.Quantity
dr("Total") += (xl.Quantity * xl.Value)
Else
' new transaction item, add it:
dt.Rows.Add(xl.EPOS, xl.Unit, xl.Quantity,
xl.Value, (xl.Quantity * xl.Value), xl.DateSale)
End If
This is pretty concise, because as you read data from XL, it is added to the Summary. There is no need to import all the detail data (XLS rows) into a collection or datatable before you perform the rollup.
B. Use Linq instead of the XLRow structure
For this omit the Primary Key in the DataTable. In this case, the DataTable would collect the raw XLS data instead of the XLRow structure. Do convert to numerics for the rollup. Next, use linq to summarize the data; perhaps into another DataTable. Example:
Sample Data:
dt.Rows.Add(10001, "Ginger Ale", 1, 2.25, #4/5/2015#)
dt.Rows.Add(34582, "Pepsi", 3, 6.0, #4/5/2015#)
dt.Rows.Add(10002, "Chips", 1, 3.25, #4/5/2015#)
dt.Rows.Add(34582, "Pepsi", 1, 2.0, #4/5/2015#)
dt.Rows.Add(78301, "Roast Duck", 1, 15.25, #4/5/2015#)
dt.Rows.Add(34582, "Pepsi", 1, 2.0, #4/5/2015#)
dt.Rows.Add(34582, "Pepsi", 1, 2.0, #4/5/2015#)
dt.Rows.Add(10002, "Chips", 1, 3.25, #4/5/2015#)
dt.Rows.Add(34582, "Pepsi", 1, 2.0, #4/5/2015#)
To get the summary info:
' group the data by EPOS code
Dim drs = From row In dt.AsEnumerable()
Group row By ID = row.Field(Of Integer)("EPOS") Into Group
Select Group
Dim TotSales As Decimal
Dim TotUnits As Integer
' each DRS is a collection of all the items with the same EPOS code
Dim dr As DataRow()
Console.WriteLine("EPOS Item Lines Units Total Sales")
' get the total sales in each group
For n As Integer = 0 To drs.Count - 1
dr = drs(n) ' the current EPOC group
TotUnits = dr.Sum(Function(t) t.Field(Of Integer)("Quantity"))
' Sales could just be TotUnits * dr(0)("Value")
' sample data makes it unclear if Value is the UNITPRICE or SALEAMOUNT
' This assumes it is SALEAMOUNT such that 2 Pepsi = 4.00
TotSales = dr.Sum(Function(t) t.Field(Of Decimal)("Value"))
' ToDo: do something interesting with the totals
Console.WriteLine("{0} {1} {2} {3} {4}",
dr(0)("EPOS"),
dr(0)("Unit").ToString,
dr.Length.ToString("D2"),
TotUnits.ToString,
TotSales.ToString("C2"))
Next
The output:
EPOS Item Lines Units Total Sales
10001 Ginger Ale 01 1 $2.25
34582 Pepsi 05 7 $14.00
10002 Chips 02 2 $6.50
78301 Roast Duck 01 1 $15.25
The key is that it does act much like SUMIF once you have the Typed data in a useful structure. The result shows that the data has 5 Pepsi entries, 7 total units and 7*2 = 14.
I think the loop version is slightly easier to manage and debug, and it much more economical since the Summary is built on the fly as XLS rows are read in.