using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    private static IEnumerable<DriverDetailsSourceObject> DriverDetails { get; set; } = Enumerable.Empty<DriverDetailsSourceObject>();

    private static IEnumerable<DriverDetailsView> DriverDetailsByOption { get; set; } = Enumerable.Empty<DriverDetailsView>();

    public static void Main()

    {

        DriverDetails = new List<DriverDetailsSourceObject>

        {

            new DriverDetailsSourceObject { Name = "RoadAssistance A", GroupName = "Group A" },

            new DriverDetailsSourceObject { Name = "RoadAssistance A", GroupName = "Group B" },

            new DriverDetailsSourceObject { Name = "RoadAssistance A", GroupName = "Group B" },

            new DriverDetailsSourceObject { Name = "RoadAssistance B", GroupName = "Group A" },

        };

​

        DriverDetailsByOption = DriverDetails.GroupBy(o => o.Name)

                                     .Select(d => 

                                           new DriverDetailsView

                                               { 

                                                   Name = d.Key,

                                                   GroupName = String.Join(",", d.Select(x => x.GroupName).Distinct()),

                                                   Count = d.Count()

                                                });

        FiddleHelper.WriteTable(DriverDetailsByOption);

    }

}

​

public class DriverDetailsSourceObject

{

    public string Name { get; set; }

    public string GroupName { get; set; }

    public DateTime DateOfPurchase { get; set; }

    public int Count { get; set; } = 1;

}

​

public class DriverDetailsView

{

    public string Name { get; set; }

    public string GroupName { get; set; }

    public DateTime DateOfPurchase { get; set; }

    public int Count { get; set; } = 1;

​

    public DriverDetailsView() { }

    public DriverDetailsView(DriverDetailsSourceObject source)

    {

        Name = source.Name;

        GroupName = source.GroupName;

        DateOfPurchase = source.DateOfPurchase;

        //Count = source.Count;

    }

}