remove duplicates from dgv?

[medlarelart]

hello, i use csv file to populate my dgv. now i wanna eliminate duplicates from my dgv. i knew it could be done using unique datatable. but i wanna eliminate it from dgv not from the dataset or datatable.
to understand it in better way- i wanna check column1 if the vales in column 1 are repeated then the entire row must be deleted i.e the duplicate row must be deleted( if column 1 has 2 duplicate values then 1 row must be deleted)
please i am waiting for a solution.

[kevininstructor]

The code works on a single column in a DataGridView. A ComboBox list each column name in the DataGridView which is used to get duplicates.

The code requires a DataGridView with three columns (note form load event populates the rows).

Not sure of how much will make sense or not but as the image below shows it works.

Hope that helps.

Form code

Public Class frmMainForm
    Private Sub cmdRemoveDupRows_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdRemoveDupRows.Click
        Dim Items = (From T In DataGridView1.Rows.Cast(Of DataGridViewRow)() Select CStr(T.Cells(ComboBox1.Text).Value)).ToArray
        Dim Items1 = Items.ListDuplicates

#If KSG_SHOW Then
        ' for debugging only, will display to IDE output window if KSG_SHOW is defined
        If Items1.Count > 0 Then
            For Each Ele In Items1
                For row As Integer = 0 To Ele.List.Count - 1
                    Console.WriteLine("[{0}] [{1}]", Ele.Item, Ele.List(row))
                Next
            Next
        End If
        Console.WriteLine()
#End If

        ' Distinct list of dups from above
        Dim noduplicates = Items1.Distinct(New DuplicateItemComparer)

        ' Used in MyRows LINQ statement which collects only DataGridView rows that are dups
        Dim GetRidOfTheseRowsList As New List(Of Integer)

        For Each item In noduplicates
            GetRidOfTheseRowsList.Add(item.List(0))
        Next

        Dim MyRows = (From T In DataGridView1.Rows.Cast(Of DataGridViewRow)() Where GetRidOfTheseRowsList.Contains(T.Index)).ToList
        If MyRows.Count > 0 Then
            If My.Dialogs.Question("Remove rows?") Then
                For Each row In MyRows
                    DataGridView1.Rows.Remove(row)
                Next
            End If
        Else
            My.Dialogs.InformationDialog("No duplicates for column " & ComboBox1.Text)
        End If


    End Sub
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        DataGridView1.Rows.Add(New Object() {"1", "A", "AAA"})
        DataGridView1.Rows.Add(New Object() {"9", "B", "BBB"})
        DataGridView1.Rows.Add(New Object() {"1", "C", "CCC"})
        DataGridView1.Rows.Add(New Object() {"2", "D", "DDD"})
        DataGridView1.Rows.Add(New Object() {"2", "E", "EEE"})

        ComboBox1.DataSource = (From T In DataGridView1.Columns.Cast(Of DataGridViewColumn)() Select T.Name).ToList

        ActiveControl = cmdRemoveDupRows
    End Sub
End Class

Add the following file DuplicateItem.vb

Public Class DuplicateItem
    Public Property Item As String
    Public Property List As New List(Of Int32)
    Public Sub New()
    End Sub
    Public Overrides Function ToString() As String
        Return String.Join(",", List.ToArray)
    End Function
End Class
Public Class DuplicateItem1
    Public Property Value As String
    Public Property Index As String
    Public Sub New()
    End Sub
End Class
Public Class DuplicateItemComparer
    Implements IEqualityComparer(Of DuplicateItem)

    Public Function Equals1(ByVal x As DuplicateItem, ByVal y As DuplicateItem) As Boolean _
        Implements IEqualityComparer(Of DuplicateItem).Equals

        ' Check whether the compared objects reference the same data.
        If x Is y Then Return True

        'Check whether any of the compared objects is null.
        If x Is Nothing OrElse y Is Nothing Then Return False

        ' Check whether the items' properties are equal.
        Return (x.Item = y.Item)
    End Function

    Public Function GetHashCode1(ByVal Item As DuplicateItem) As Integer Implements IEqualityComparer(Of DuplicateItem).GetHashCode
        ' Check whether the object is null.
        If Item Is Nothing Then Return 0

        ' Get hash code for the item field if it is not null.
        Dim hashForItem = If(Item.Item Is Nothing, 0, Item.Item.GetHashCode())

        ' Calculate the hash code for the item.
        Return hashForItem
    End Function
End Class

Add the following file DuplicateListerCode.vb

Module DuplicateListerCode
    <System.Diagnostics.DebuggerStepThrough()> _
    <System.Runtime.CompilerServices.Extension()> _
    Public Function ListDuplicates(ByVal sender As String()) As List(Of DuplicateItem)
        Dim Result As New List(Of DuplicateItem)

        Dim q = From value In sender.Select(Function(v, index) New With {.value = v.ToUpper, .index = index}) _
                Group By value.value Into Group _
                Where Group.Count > 1

        For Each item In q
            Dim LineList As New List(Of Int32)

            For Each item2 In item.Group
                LineList.Add(item2.index)
            Next

            Result.Add(New DuplicateItem With {.Item = item.value, .List = LineList})
        Next

        Return Result

    End Function
End Module

Add the following file MyDialogs.vb

Namespace My
    ''' <summary>
    ''' Contains wrappers for common dialog operations where the intent is to keep
    ''' method based and easy to maintain.
    ''' </summary>
    ''' <remarks></remarks>
    <Global.System.ComponentModel.EditorBrowsable(Global.System.ComponentModel.EditorBrowsableState.Never)> _
    Partial Friend Class _Dialogs
        ''' <summary>
        ''' Defaults to Tilde, used for breaking lines in dialogs
        ''' </summary>
        ''' <value></value>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Property LineBreakChar As String = "~"
        Private Function CreateLineBreaks(ByVal Text As String) As String
            Return Text.Replace(LineBreakChar, Environment.NewLine)
        End Function
        Public Function Question(ByVal Text As String) As Boolean
            Return _
                (
                    MessageBox.Show(CreateLineBreaks(Text),
                                    My.Application.Info.Title,
                                    MessageBoxButtons.YesNo, MessageBoxIcon.Question,
                                    MessageBoxDefaultButton.Button2) = MsgBoxResult.Yes)
        End Function

        ''' <summary>
        ''' Shows text in dialog with information icon
        ''' </summary>
        ''' <param name="Text">Message to display</param>
        ''' <remarks></remarks>
        Public Sub InformationDialog(ByVal Text As String)
            MessageBox.Show(Text, My.Application.Info.Title, MessageBoxButtons.OK, MessageBoxIcon.Information)
        End Sub
    End Class
    <Global.Microsoft.VisualBasic.HideModuleName()> _
    Friend Module KSG_Dialogs
        Private instance As New ThreadSafeObjectProvider(Of _Dialogs)
        ReadOnly Property Dialogs() As _Dialogs
            Get
                Return instance.GetInstance()
            End Get
        End Property
    End Module
End Namespace

[Zmcpherson]

couldnt you just do this?

For x As Integer = 0 To DataGridView1.Rows.Count - 2
            For y As Integer = x + 1 To DataGridView1.Rows.Count - 1
                If DataGridView1.Item(0, x).Value = DataGridView1.Item(0, y).Value Then
                    DataGridView1.Rows.RemoveAt(y)
                End If
            Next
        Next

err... maybe this...

For x As Integer = 0 To DataGridView1.Rows.Count - 2
            For y As Integer = DataGridView1.Rows.Count - 1 to x + 1 step -1
                If DataGridView1.Item(0, x).Value = DataGridView1.Item(0, y).Value Then
                    DataGridView1.Rows.RemoveAt(y)
                End If
            Next
        Next

[medlarelart]

Hi all, both the codes provided by kevin and zmcpherson works fine. Thank you for the quick response. I am gonna rate it high. But one problem still in removing the duplicates - if the column 1 has the values college and COLLEGE it is not removing the duplicate.it assumes it as case sensitive.But i need it to be deleted.it must not check on the case sensitive.Any solution would be highly helpful.

[kevininstructor]

Hi all, both the codes provided by kevin and zmcpherson works fine. Thank you for the quick response. I am gonna rate it high. But one problem still in removing the duplicates - if the column 1 has the values college and COLLEGE it is not removing the duplicate.it assumes it as case sensitive.But i need it to be deleted.it must not check on the case sensitive.Any solution would be highly helpful.

I just tried using the following pointing to Column1 for removal.

DataGridView1.Rows.Add(New Object() {"college", "A", "1"})
DataGridView1.Rows.Add(New Object() {"Delphi", "B", "2"})
DataGridView1.Rows.Add(New Object() {"COLLEGE", "A", "1"})
DataGridView1.Rows.Add(New Object() {"Perl", "C", "2"})

The rows left Delphi, College and Perl.