CODEWITHSUNDEEP
vb.netlistmerge
Shiva
Shiva

Reputation: 235

How to merge two list to have a distinct list without duplicate values in vb.net

I have this problem in vb.net. Lets say I got 2 Lists ListA and ListB both holds objects of same type.

Eg., one of the property of the object is ID. (ID is written in brackets)

 ListA              ListB
--------------------------- 
A(3818)            A(3818)  
B(3819)            B(3819)  
C(3820)            C(3820)  
D(3821)            D(3821)  
E(3823)            F(0)  
H(3824)            G(0)  
I(3825)

How do I merge these two Lists to have a new distinct list which holds objects only once whose ID matches and all other objects(whose ID dont match) are simply added to the new list.

Sample output be,

New List  
--------  
A(3818)  
B(3819)  
C(3820)  
D(3821)  
E(3823)  
F(0)  
G(0)  
H(3824)  
I(3825)

When I searched I found that AddRange() and Union are some of the methods to do the merge. But i am not able to find if this works for non standard objects(apart from Integer, String)

Upvotes: 1

Views: 7834

Answers (4)

Allan Blackford
Allan Blackford

Reputation: 93

For each item as String in ListA 
   If Not ListB.Contains(item) Then 
      ListB.Add(item)
   End If 
Next

Upvotes: 0

GDutton
GDutton

Reputation: 176

Could use a collection bucket

Dim oCol As New Collection
AddTitems(oCol, oListA)
AddTitems(oCol, olistB)
Public Function AddTitems(oSummaryList As Collection, oList As List(Of thing)) As Collection
    For Each oThing As thing In oList
        If Not oSummaryList.Contains(CStr(oThing.ID)) Then oSummaryList.Add(oList, CStr(oThing.ID))
    Next

    Return oSummaryList

End Function

Upvotes: 0

Sastreen
Sastreen

Reputation: 597

Here are a couple simple functions that should do that for you. I'm not sure how efficient they are though. I don't think there is anything built in.

Private Function nameOfFunction(list1 as list(of type), list2 as list(of type)) as list(of type)
    Dim result as new list(of type)

    for a as integer = 0 to math.max(list1.count, list2.count) - 1 step 1
        If a < list1.count AndAlso resultHasID(result, list1(a).ID) = False Then
            result.add(list1(a))    
        end if
        If a < list2.count AndAlso resultHasID(result, list2(a).ID) = False Then
             result.add(list2(a))
        end if
    next
End Function

Private Function resultHasID(testList as list(of type), s as string) as boolean
    Dim result as Boolean = False
    for a as integer = 0 to testlist.count - 1 step 1
        if(testlist(a).ID = s) then
            result = true
            exit for
        End if
    Next
    Return result
End function

Upvotes: 0

Archlight
Archlight

Reputation: 2079

Use addRange() and then linq with distinct to filter out the duplicates.

Dim b = YourCollection.Distinct().ToList()

Upvotes: 2

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