using System.Collections.Generic;
public string Company { get; set; }
public double Weight { get; set; }
public long TrackingNumber { get; set; }
public static void Main()
{ new Package { Company = "Coho Vineyard",
Weight = 25.2, TrackingNumber = 89453312L },
new Package { Company = "Lucerne Publishing",
Weight = 18.7, TrackingNumber = 89112755L },
new Package { Company = "Wingtip Toys",
Weight = 6.0, TrackingNumber = 299456122L },
new Package { Company = "Contoso Pharmaceuticals",
Weight = 9.3, TrackingNumber = 670053128L },
new Package { Company = "Wide World Importers",
Weight = 33.8, TrackingNumber = 4665518773L } };
.ToLookup(p => Convert.ToChar(p.Company.Substring(0, 1)),
p => p.Company + " " + p.TrackingNumber);
Console.WriteLine(Newtonsoft.Json.JsonConvert.SerializeObject(lookup));