使用LINQ从列表中获取具有特定属性最大值的对象

Question

I have a list of Beam objects. Each Beam class has X , Y properties for coordinates and it also has a Height property.

Now here is my initial list:

List1 = {beam1, beam2, beam3, beam4}

beam1 = {X = 0, Y = 0, Height = 40}
beam2 = {X = 200, Y = 0, Height = 40}
beam3 = {X = 200, Y = 0, Height = 60}
beam4 = {X = 400, Y = 0, Height = 40}

As you can see beam2 and beam3 are at the same point, I want a list where I only have the beam with the maximum Height at each distinct point.

So the final list using LINQ would be:

 List2 = {beam1, beam3, beam4}

Answer 1

You can use GroupBy to group them based on X and Y and select the item with the maximum Height from each group:

beams.GroupBy(b => new { b.X, b.Y })
 .Select(g => g.First(x => x.Heigth == g.Max(h => h.Height)))
 .ToList();

Personally I would use MaxBy method to get the beam with max. Height:

beams.GroupBy(b => new { b.X, b.Y })
 .Select(g => g.MaxBy(x => x.Heigth))
 .ToList();

Answer 2

尝试这个：-

var query = List1.GroupBy(x => new { x.X, x.Y }).Select(x => x.First(y => y.Height == x.Max(z => z.Height)));