using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

​

    static List<Project> Projects = new List<Project> {

                                                        new Project { Id = 1, IdPlateforme = 1, IdSecteur = 1},

                                                        new Project { Id = 2, IdPlateforme = 1, IdSecteur = 2},

                                                        new Project { Id = 3, IdPlateforme = 1, IdSecteur = 4},

                                                        new Project { Id = 4, IdPlateforme = 3, IdSecteur = 1},

                                                        new Project { Id = 5, IdPlateforme = 3, IdSecteur = 2},

                                                        new Project { Id = 6, IdPlateforme = 3, IdSecteur = 4},

                                                        new Project { Id = 7, IdPlateforme = 2, IdSecteur = 1},

                                                        new Project { Id = 8, IdPlateforme = 2, IdSecteur = 2},

                                                        new Project { Id = 9, IdPlateforme = 2, IdSecteur = 4},

                                                    };

    public static void Main()

    {

​

        var results = Projects.Select(x => new {x.Id, x.IdPlateforme, x.IdSecteur, IdPlateformeSecteur = SetIdPlatformeSecteur(x.IdPlateforme, x.IdSecteur)});

​

        foreach(var r in results)

        {

            Console.WriteLine(r);

        }

    }

        static Func<int, int, int> SetIdPlatformeSecteur = (p, s) =>

        {

            int r = (p, s) switch

            {

​

                _ when p == 1 && s == 1 => 1,

                _ when p == 1 && s == 2 => 2,

                _ when p == 1 && s == 4 => 3,

                _ when p == 3 && s == 1 => 4,

                _ when p == 3 && s == 2 => 5,

                _ when p == 3 && s == 4 => 6,

                _ when p == 2 && s == 1 => 7,

                _ when p == 2 && s == 2 => 8,

                _ when p == 2 && s == 4 => 9,

                _ => throw new ArgumentException(message: "Id combination not recognized", paramName: $"{p} {s}")

​

            };

​

            return r;

        };

​

}

    public class Project

    {

        public int Id { get; set; }

        public int IdPlateforme { get; set; }

        public int IdSecteur  { get; set; }

    }