using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var people = new[]

                    {

                        new

                            {

                                Name = "Vernon",

                                Gender = "Male",

                                City = "London",

                            },

                        new

                            {

                                Name = "Carrie",

                                Gender = "Female",

                                City = "London"

                            },

                            new

                            {

                                Name = "Joanna",

                                Gender = "Female",

                                City = "London"

                            },

                        new

                            {

                                Name = "Thomas",

                                Gender = "Male",

                                City = "Paris"

                            }

                    };

​

        var peopleByGender = from p in people

                             group p by new { p.Gender, p.City } // this is how to group by multiple properties

                             into g

                             select new

                             {

                                City = g.Key.City,

                                Gender = g.Key.Gender,

                                People = g

                             };

        foreach (var group in peopleByGender)

        {

            Console.WriteLine("{0} {1}", group.Gender, group.City);

            foreach (var peopleInGroup in group.People)

            {

                Console.WriteLine("  {0} {1} {2}", peopleInGroup.Gender, peopleInGroup.City, peopleInGroup.Name);

            }

        }

    }

}