using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

     public class Field

        {

            public  double X { get; set; }

​

            public  double Y { get; set; }

        }

    public static void Main()

    {

        var items = new List<Field>()

            {

                new Field() {Y = 2.817685, X = 1.546723},

                new Field() {Y = 2.818071, X = 1.534915},

                new Field() {Y = 2.818433, X = 1.523118},

                new Field() {Y = 2.82685, X = 1.52028},

                new Field() {Y = 2.830284, X = 1.524813},

                new Field() {Y = 2.831784, X = 1.536945},

                new Field() {Y = 2.846398, X = 1.52745},

                new Field() {Y = 2.846483, X = 1.515903},

                new Field() {Y = 2.846957, X = 1.504912},

            }.OrderBy(p => p.Y).ToList();

​

            var topRow = items.Take(3).OrderBy(p => p.X);

            var middleRow = items.Skip(3).Take(3).OrderBy(p => p.X);

            var bottomRow = items.Skip(6).Take(3).OrderBy(p => p.X);

    }

}