Question

我有List，其中包含Beam类的实例。每个Beam对象都有Elevation属性。

List<Beam> Beams = new List<Beam> {Beam1, Beam2, ...};

public class Beam
{
    public double Elevation;
}

现在我想创建一个包含不同高程的List<double>。例如，如何编写一个接受Beams列表的方法，如下所示

var Beam1 = new Beam { Elevation = 320);
var Beam2 = new Beam { Elevation = 320);
var Beam3 = new Beam { Elevation = 640);
var Beam4 = new Beam { Elevation = 0);

List<Beam> Beams = new List<Beam> {Beam1, Beam2, Beam3, Beam4};

并删除重复的高程：

listOfElevations = {0, 320,640}

Answer 1

使用Linq - 特别是Enumerable.Distinct()方法是关键：

var listOfElevations  = beams.Select(x => x.Elevation) //project to Elevations
                             .Distinct() // pick only distinct ones
                             .ToList(); //make it a list

Answer 2

使用LinQ非常简单：

var listOfElevations = Beams.Select(x => x.Elevation).Distinct().ToList();

您选择了Elevation的值，选择Distinct值，将其设置为List，因为它是您的预期输出。

Answer 3

    List<Beam> Beams = new List<Beam> {Beam1, Beam2, Beam3, Beam4};
        var differentBeams = Beams.Select(b => b.Elevation).Distinct().ToList();

Answer 4

使用LINQ的另一种方法，如果您有多个属性并希望获得唯一列表，这可能很有用

beams.GroupBy(x => x.Elevation).Select(g => g.Key);

Answer 5

1）使Beam实现IComparable：

public class Beam : IComparable
{
    public double Elevation; //consider changing this to property, btw.

    public int CompareTo(object obj) {
         if (obj == null) return 1;

         Beam otherBeam = obj as Beam;
         return this.Elevation.CompareTo(otherBeam.Elevation);
    }
}

2）使用Distinct（）：

var listOfElevations = Beams.Distinct().Select(x=> x.Elevation).ToList();

从List <object> </object>中获取不同的值

5 个答案: