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我们需要将以下逻辑形式的数据存储到一个类中：

"description 1", "activity A", "service A", Month 1 cost, month 2 cost, month 3 cost etc....

所以我有一个类对象，如下所示：

Public Class EntityTableRow
    Public Description As String
    Public Activity As String
    Public M1 as Double
    Public M2 as Double
    .....
End Class

M... 属性将根据源数据（excel 数据源）中的月份数来持有每月成本。从逻辑上讲，上述类将保存类似于上述逻辑形式的数据

现在我需要根据相同的列对行进行分组，并汇总每月的成本。

为此，我正在尝试使用以下 Linq 查询：

Dim a As New List(Of EntityTableRow) 
        a = myTable1.TableRows 
        Dim lFinal2 = From el In a Group el By Key = New With {Key el.Description, Key el.Activity} Into Group _ 
                      Select New With {.Activity = Key.Description, _ 
                                       .Country = Key.Activity, _ 
                                       .M1 = Group.Sum(Function(x) x.M1), _ 
                                       .M2 = Group.Sum(Function(x) x.M2)}

这似乎工作正常，现在我该如何更改上面的 Linq 查询，对于下面的修改类，我需要将月份成本存储在字典中，并且仍然得到分组的行，并在不同的月份列上求和？

Public Class EntityTableRow
        Public Description As String
        Public Activity As String
        Public MonthCosts As New Dictionary(Of Integer, Double)
    End Class
4

2 回答 2

1 
Dim lFinal2 = From el In a
              Group el By Key = New With {Key el.Description, Key el.Activity} Into Group
              Select New With {
                  .Activity = Key.Description,
                  .Country = Key.Activity,
                  .MonthCost =
                      (From k In Group.SelectMany(Function(g) g.MonthCosts.Keys).Distinct()
                       Select New With {
                            .Month = k,
                            .Sum = Group.Sum(Function(g) If(g.MonthCosts.ContainsKey(k), g.MonthCosts(k), 0))
                       }).ToDictionary(Function(i) i.Month, Function(i) i.Sum)
              }

简单的测试数据：

Dim a As New List(Of EntityTableRow) From {
    New EntityTableRow With {.Activity = "A", .Description = "D", .MonthCosts = New Dictionary(Of Integer, Double) From {{1, 20}, {2, 20}, {3, 20}}},
    New EntityTableRow With {.Activity = "A", .Description = "D", .MonthCosts = New Dictionary(Of Integer, Double) From {{2, 20}, {3, 20}, {4, 20}}}
}

结果： 在此处输入图像描述

于 2013-03-19T17:32:54.470 回答
-3

在我看来，您的初始数据类型应该采用以下形式

Public Class EntityTableRow
    Public Description As String
    Public Activity As String
    Public MonthCosts As IEnumerable(Of Decimal)
End Class

我将向您展示如何从订单中的一个IEnumerable(Of Decimal)和组中进行选择。这应该说明 IEnumerable 可以表示有序数据，具体取决于实现者。首先，我将扩展EntityTableRow类定义。使用不可变类有很大的好处，您应该同意直接公开没有属性的成员变量被认为是不好的做法。

Public Class EntityTableRow

    Private ReadOnly _descritption As String
    Private ReadOnly _activity As String
    Private ReadOnly _monthCosts As IList(Of Decimal)

    Public Sub New( _
            ByVal description As String,
            ByVal activity As String, _
            ByVal monthCosts As IEnumerable(Of Decimal))
        Me._description = description
        Me._activity = activity
        Me._monthCosts = New List(Of Decimal)(monthCosts)
    End Sub

    Public ReadOnly Property Description() As String
        Get
            Return Me._description
        End Get
    End Property

    Public ReadOnly Property Activity() As String
        Get
            Return Me._activity
        End Get
    End Property

    Public ReadOnly Property MonthCosts() As IEnumerable(Of Decimal)
        Get
            Return Me._monthCosts
        End Get
    End Property
End Class

您可以看到该类仅公开IEnumerable(Of Decimal)，但此序列确实表示有序数据。现在我将展示如何使用 linq 对IEnumerable(Of EntityTableRow)使用此定义的数据进行分组。

首先，我将创建一些测试数据。

Dim testData As IEnumerable(Of EntityTableRow) = _
    {
        New EntityTableRow("A", "B", New Decimal() {20, 20, 20}),
        New EntityTableRow("A", "B", New Decimal() {Nothing, 20, 20, 20}),
        New EntityTableRow("C", "D", New Decimal() {10, 20, Nothing, 40}),
        New EntityTableRow("C", "D", New Decimal() {50, 60})
    }

在这一点上，我认为这IList将为稀疏的数据群体提供更好的支持，但这在原始问题中没有定义。这些示例单调地从一个开始。

有几种方法可以执行分组，我将把它分成三个简单的步骤，我希望很容易理解。请记住，这都是懒惰的评估。

首先，将数据展平到月份级别，将月份编号合并到序列中。

 Dim allCosts = testData.SelectMany( _
     Function(r) r.MonthCosts.Select( _
         Function(c, i) New With {r.Descriptionr, r.Activity, .Month = i, .Cost = c}))

请注意使用索引Select扩展从订单中推断月份。

接下来，按活动、描述和月份对成本进行分组和汇总，

Dim groupedCosts = allCosts.GroupBy( _
    Function(r) New With {r.Activity, r.Description, r.Month},
    Function(k, s) New With
        {
            k.Description,
            k.Activity,
            k.Month,
            .TotalCost = s.Sum(Function(r) r.Cost)
        })

这实际上为您提供了所需的信息，如果仍然需要，您可以通过描述和活动重新组合月份，

Dim groupedDescriptionActivities = groupedCosts.GroupBy( _
    Function(r) New With {r.Description, r.Activity}, _
    Function(k, s) New With
        {
            k.Description,
            k.Activity,
            .MonthCosts = s.Select(Function(r) New With {r.Month, r.TotalCost})
        })
于 2013-03-19T17:30:25.157 回答