Question

我有一个需要削减的对象列表。这些项目是可变的，所以我不能强行它。

这是我想要做的......

原始对象列表......

"Name":"Apple","Qty":1
"Name":"Banana","Qty":2
"Name":"Apple","Qty":3
"Name":"Banana","Qty":4
"Name":"Strawberry","Qty":5

削减后的对象列表......

"Name":"Apple","Qty":4
"Name":"Banana","Qty":6
"Name":"Strawberry","Qty":5

我在.net 4.5环境中工作，所以我对任何方法都持开放态度。

Answer 1

所以你有一个具有Name和Qty属性的对象列表？您可以使用group by和aggregate：

var items = list _
     .GroupBy(Function(i) i.Name)  _
     .Select(Function(i) new Item With { .Name = i.Key, .Qty = i.Sum(Function(q) q.Qty) })

按名称分组，然后您可以使用Sum汇总项目总数。你也可以从another example看到这个。

Answer 2

您可以查看创建一个字典，该字典将名称存储为键，然后编号为值：

Private _dict As Dictionary(Of String, Integer)
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click

    _dict = New Dictionary(Of String, Integer)

    AddToDictionary("Apple", 1)
    AddToDictionary("Banana", 2)
    AddToDictionary("Apple", 3)
    AddToDictionary("Banana", 4)
    AddToDictionary("Strawberry", 5)


    'The following outputs:
    'Apple : 4
    'Banana : 6
    'Strawberry : 5

    For Each kvp In _dict
        Debug.WriteLine(kvp.Key & " : " & kvp.Value)
    Next
End Sub

Private Sub AddToDictionary(name As String, value As Integer)
    If _dict.ContainsKey(name) Then
        _dict(name) += value
    Else
        _dict.Add(name, value)
    End If
End Sub

Vb.net削减了对象列表

2 个答案: