Imports System

imports System.Linq

imports System.Collections.Generic

Public Module Module1

    Public Sub Main()

        Dim merge_list As New List(Of Employee)

        Dim _list1 As New Employee

        _list1.EmployeeId = 1

        _list1.EmployeeName = "Adam"

        _list1.City = "London"

        _list1.Gender = "Male"

        merge_list.Add(_list1)

​

        Dim _list2 As New Employee

        _list2.EmployeeId = 2

        _list2.EmployeeName = "Mary"

        _list2.City = "Washington"

        _list2.Gender = "Female"

        merge_list.Add(_list2)

​

        Dim _list3 As New Employee

        _list3.EmployeeId = 3

        _list3.EmployeeName = "Bob"

        _list3.City = "Paris"

        _list3.Gender = "Male"

        merge_list.Add(_list3)

​

        Dim _list4 As New Employee

        _list4.EmployeeId = 4

        _list4.EmployeeName = "Paul"

        _list4.City = "Paris"

        _list4.Gender = "Male"

        merge_list.Add(_list4)

​

        Dim groups = merge_list.GroupBy(Function(t) New With {Key t.City,

                                      Key t.Gender}) _

                                      .Where(Function(grp) grp.Count > 1)

​

        For Each item In groups

            Console.WriteLine(item.Key.City)

            For Each inneritem In item

                Console.WriteLine(inneritem.EmployeeName)

            Next

        Next

    End Sub

    Class Employee

        Public Property EmployeeId As Integer

        Public Property EmployeeName As String

        Public Property City As String

        Public Property Gender As String

    End Class

End Module