CODEWITHSUNDEEP
vb.net
JkAlombro
JkAlombro

Reputation: 1834

Simplified way to find duplicates in list of objects in vb.net and merge them

I have an API that accepts a list of objects(Object contains ProductID and Quantity). I want to determine whether there are duplicate product ID on the passed list. If duplicates are found, I'll merge them by adding the Quantity of duplicate product ID. To do this, I created my own algorithm that loops the list one-by-one then store it to another list (the verified one). The code goes like this.

For Each passedVoucher As VoucherInfo In VouchersToRelease

     indexofduplicate = 0
     sumQuantity = 0
     hasDuplicate = False

     If VerifiedReleasedVouchers.Count() > 0 Then

         'for loop that checks if productID exists in the VerifiedReleasedVouchers
          For Each finalList As VoucherInfo In VerifiedReleasedVouchers

            If passedVoucher.ProductID = finalList.ProductID Then
                 indexofduplicate = VerifiedReleasedVouchers.IndexOf(finalList)

                 'if true, adds the Quantity of duplicate to the existing quantity at the VerifiedReleasedVouchers 
                 sumQuantity = Convert.ToInt32(VerifiedReleasedVouchers(indexofduplicate).Quantity) + Convert.ToInt32(passedVoucher.Quantity)

                 VerifiedReleasedVouchers(indexofduplicate).Quantity = sumQuantity.ToString

                 hasDuplicate = True
                 Exit For
            End If
         Next
      End If

      'adds the voucher to verified released voucher if no duplicate was found
      If hasDuplicate = False Then
         VerifiedReleasedVouchers.Add(passedVoucher)
      End If

 Next

So what I did is, I ForEach looped the passed list. Inside the loop, I compared the current object from the passedList into every object in the verifiedList(w/c is empty by default) to determine whether their are duplicate product ID. If no duplicate was found, i'll just add the current object to the verifiedList. If duplicate was found, ill just update the object from the verified list with the same ProductID by storing the sum of the Quantity of both objects.

The code above works perfectly as intended but the thing is, it performs a lot of tasks. Is there any way to simplify what I did above?

P.S. List.Distinct() is not a solution for this

Upvotes: 0

Views: 858

Answers (1)

Pikoh
Pikoh

Reputation: 7713

You could use Linq to easily achieve what you want. First you must GroupBy ProductID and then Select all the groups with a sum of the quantity. Finally, we get a list:

Dim VerifiedReleasedVouchers As List(Of VoucherInfo) = VouchersToRelease.GroupBy(Function(x) x.ProductID).[Select](Function(y) New VoucherInfo() With {
.ProductID = y.Key,
.Quantity = y.Sum(Function(z) z.Quantity),
.Denom = y.First().Denom
}).ToList()

Upvotes: 1

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