using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var people = new[]

                {

                    new { Name = "Vernon", Gender = "Male", CountryCode = "GB" },

                    new { Name = "Carrie", Gender = "Female", CountryCode = "CA" },

                    new { Name = "Joanna", Gender = "Female", CountryCode = "US" },

                    new { Name = "Thomas", Gender = "Male", CountryCode = "ES" },

                    new { Name = "James", Gender = "Male", CountryCode = "GB" },

                    new { Name = "Elly", Gender = "Female", CountryCode = "US" }

                };

​

​

        var countries = new[]

        {

                new {CountryName = "United Kingdom", Code = "GB"},

                new {CountryName = "United States", Code = "US"},

                new {CountryName = "Canada", Code = "CA"},

                new {CountryName = "France", Code = "FR"},

                new {CountryName = "Spain", Code = "ES"}

        };

​

​

​

​

        var results = countries.GroupJoin(people, arg => arg.Code, 

                                                  arg => arg.CountryCode, 

                                                  (country, p) => new { Country = country, PeopleInCountry = p });

        foreach (var r in results)

        {

            Console.WriteLine(r.Country.CountryName);

            foreach (var person in r.PeopleInCountry)

            {

                Console.WriteLine("  {0}", person.Name);

            }

        }

    }

}