Question

I have a list of objects, each with 2 relevant properties: "ID" and "Name". Lets call the list "lstOutcomes". I need to check the list for duplicates (meaning object1.ID = object2.ID, etc.) and set a flag (valid = false, or something) if there is at least one duplicate. Also, it would be nice to send a message to the user mentioning the "Name" of the object, when it fails.

我相信,我需要使用<代码>。专家组通过进行这项工作,但我没有在准则和准则中这样做,所列举的例子仅仅无助于我。第条似乎接近于需要,但并非完全需要,而是载于C#。

......

Dim duplist = _
    (From o As objectType In lstOutcomes _
    Group o By o.ID Into g = Group _
    Let dups = g.Where(Function(h) g.Count > 1) _
    Order By dups Descending).ToArray

if duplist.count > 0 then
valid = false
end if

帮助?

Answer 1

这个项目已经结束,我只是这样说:

      For each outcome, if it is in the list of valid outcomes more than once, and it is not in the list of 
      duplicates, add it to the duplicates list.
    Dim lstDuplicates As New List(Of objectType)
    For Each outcome As objectType In lstOutcomes
         declare a stable outcome variable
        Dim loutcome As objectType = outcome
        If lstOutcomes.Where(Function(o) o.ID = loutcome.ID).Count > 1 _
        AndAlso Not lstDuplicates.Where(Function(d) d.ID = loutcome.ID).Count > 0 Then
            lstDuplicates.Add(outcome)
        End If
    Next
    If lstDuplicates.Count > 0 Then
        valid = False
        sbErrors.Append("There cannot be multiple outcomes of any kind. The following " & lstDuplicates.Count & _
                        " outcomes are duplicates: ")
        For Each dup As objectType In lstDuplicates
            sbErrors.Append("""" & dup.Name & """" & " ")
        Next
        sbErrors.Append("." & vbNewLine)
    End If

Answer 2

我用C#书写,但希望你能够将其改为VB。它不使用并使用O(nlog n),我假定你有。 List<T>:

lst.Sort();  //O(nlogn) part.

var duplicatedItems = lst.Skip(1).Where((x,index)=>x.ID == lst[index].ID);

Answer 3

Dim itemsGroupedByID = lstOutcomes.GroupBy(Function(x) x.ID)
Dim duplicateItems = itemsGroupedByID.Where(Function(x) x.Count > 1) _
                                     .SelectMany(Function(x) x) _
                                     .ToList()

If duplicateItems.Count > 0
    valid = False
    Dim errorMessage = "The following items have a duplicate ID: " & _
                       String.Join(", ", duplicateItems.Select(Function(x) x.Name))
End If

Answer 4

我拿回了C#中Saeed Amiri所说的话,并完成了。

        lst.Sort()
        Dim valid As Boolean = true
    dim duplicatedItems = lst.Skip(1) _
        .Where(Function(x,index) x.ID = lst(index).ID)

    Dim count As Integer = duplicatedItems.Count()
    For Each item As objectType In duplicatedItems
        valid = False
        Console.WriteLine("id: " & item.ID & "Name: " & item.Name)
    Next

Answer 5

时间已晚,但可以帮助他人。

可以通过一个非常清洁的单行器来做到这一点:

Dim lstOutcomes As IList(Of T)

Dim FoundDuplicates As Boolean
FoundDuplicates = lstOutcomes.Any(Function(p) lstOutcomes.ToArray.Count(Function(q) p.ID = q.ID and p.Name=q.Name) > 1)

Dim ListOfDuplicates As IList(Of T)
ListOfDuplicates = lstOutcomes.Where(Function(p) lstOutcomes.ToArray.Count(Function(q) p.ID = q.ID And p.Name = q.Name) > 1)

Then you can clean the list of duplicates so that it contains the duplicate only once:

Dim CleanList as IList(of T)
For Each MyDuplicate As T in ListOfDuplicates
    If not CleanList.Any(function(p) p.ID = MyDuplicate.ID And p.Name = MyDuplicate.Name) then
        CleanList.Add(MyDuplicate)
    End If
Next

Or as a one-liner, although it does not read as nicely

ListOfDuplicates.ForEach(sub(p) If not CleanList.Any(function(q) p.ID = q.ID And p.Name = q.Name) then CleanList.Add(p))

最后,作为对今后需求的预测,你应将“重复”定义为单独的事情。代表非常方便:

Dim AreDuplicates as Func(of T, T, Boolean) = Function(a,b) a.ID = b.ID And a.Name = b.Name
FoundDuplicates = lstOutcomes.Any(Function(p) lstOutcomes.ToArray.Count(Function(q) AreDuplicates(p,q) ) > 1)

友情链接