.net - Datatable linq - 获取具有最大总和值的第一行

Question

我有一个数据表（有 2 列）：

XY

AA 100

BB 150

AA 25

BB 10

抄送120

如您所见：

AA 值总和为 125

BB值总和是160

CC 值总和为 120

BB的最大总和为160

我想获得这个值，即总和的最大值，其中 sum 是一个 grup 的值，按列 X 值分组，还有那个 X 值。

如何在 VB.NET 中使用 LINQ 执行此操作？

谢谢 ！

编辑：这是我正在使用的代码：

Dim marfa = _
                        From dr In dtMarfuriT _
                        Group dr By Key = dr("MRF_COD") Into Group _
                        Let maxim = Group.Sum(Function(dr) dr("MRF_MASA_STABILITA")) _
                        Select New With { _
                             Key .cod = Key, _
                             Key .TopMarfa = Group.First(Function(dr) Group.Sum(Function(drx) CDbl(drx("MRF_MASA_STABILITA"))) = maxim)("MRF_COD"), _
                             Key .Maximul = maxim}


                Dim MasaMaxima As Double = marfa.Maximul 

                Dim CodulMaseiMaxime As String = marfa.TopMarfa

Answer 1

B a1 = new B() { Text = "AA", Number = 100};
B a2 = new B() { Text = "BB", Number = 150};
B a3 = new B() { Text = "AA", Number = 25};
B a4 = new B() { Text = "BB", Number = 10};
B a5 = new B() { Text = "CC", Number = 120};

List<B> list = new List<B>();
list.Add(a1);
list.Add(a2);
list.Add(a3);
list.Add(a4);
list.Add(a5);

var l = from i in list
    group i by i.Text into g
    let sum = g.Sum(e=>e.Number)
    orderby sum descending 
    select new
    {
        Text = g.Key,
        Sum = sum
    };

var item = l.First();

Console.WriteLine(item.Sum);



public class B
{
    public int Number{get;set;}
    public string Text{get;set;}
}

Answer 2

这是 C# 中的示例

    // sample array
    Tuple<string, int>[] arr = new Tuple<string, int>[]
        {
            new Tuple<string, int>("AA", 10),
            new Tuple<string, int>("AA", 20),
            new Tuple<string, int>("BB", 10),
            new Tuple<string, int>("BB", 60)
        };

    // calcs
    var result = arr.GroupBy(a => a.Item1)
       .Select(g => new {Key = g.Key, S = g.Select(s => s.Item2).Sum()})
       .OrderByDescending(g => g.S)
       .FirstOrDefault();

    // or
    var result1 =
        (from tuple in arr
         group tuple by tuple.Item1 into gr
         let s = gr.Select(s => s.Item2).Sum()
         orderby s descending
         select new {x = gr, y = s}).FirstOrDefault();

Answer 3

Dim result= _
     (From dr In dtX _
     Group dr By Key = dr("A") Into Group _
     Select New With { _
            Key .Code = Key, _
            SumX = Group.Select(Function(drx) CDbl(drx("B"))).SumX}) _
    .OrderByDescending(Function(g) g.SumX).FirstOrDefault

Dim MaxSumX As Double = result.SumX
Dim MaxCode As String = result.Code