Combine two list(of T) collections to contain distict objects[Answered] RSS

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  peterthegrea...

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  Combine two list(of T) collections to contain distict objects

  Dec 11, 2013 07:31 PM|peterthegreat|LINK

  Hi,

  I have the following list collection that i want to combine with another List(of Items) collection

  Dim ilistValues As IList(Of Product)

  The List(of items) should first be filtered to contain only objects that have a property Name="First"

  then joined with ilistValues collection and filtered to contain Product with DISTICT 'Email' property.

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  ignatandrei

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  Re: Combine two list(of T) collections to contain distict objects

  Dec 11, 2013 08:53 PM|ignatandrei|LINK

  var q = iListValues.Where(item=>item.Name=="First").ToList()

  See also the Distinct function

  then use addrange.

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  peterthegrea...

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  Re: Combine two list(of T) collections to contain distict objects

  Dec 13, 2013 02:34 PM|peterthegreat|LINK

  Is that related to a Custom object ?

  Because it does not work with my ILIST(OF PRODUCT)

  Also, is it possible to join two List  collections together through a Query and amalgamate into one ?

  Thanks

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  Rion William...

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  Re: Combine two list(of T) collections to contain distict objects

  Dec 13, 2013 02:56 PM|Rion Williams|LINK

  If you have two seperate collections (of the same kind of items), you can use the AddRange() method available through LINQ to merge two collections into one. In your case, you could also use LINQ to apply the necessary filtering (through the Distinct() method or otherwise) and then merge your collections : 

  'Your first collection (you can also apply filters here through a Where clause)'
  Dim a = YourCollectionOfItems.Distinct().ToList()
  
  'Your second collection'
  Dim b = YourOtherCollectionOfItems.Distinct().ToList()
  
  'Your merged collection
  Dim c = a.AddRange(b)

  So your case might look something like this : 

  'Your first collection (you can also apply filters here through a Where clause)'
  Dim firstNames = YourFirstCollection.Where(Function (f) f.FirstName = "First").ToList() 
  

  However to use a distinct on a specific property, you might want to consider using a third-party library like MoreLINQ which has a DistinctBy() method that may prove useful in a situation like this and it would allow you to get all of the objects with distinct email address values by using the following syntax : 

  Dim emailAddresses = YourCollection.DistinctBy(Function(f) f.Email).ToList()

  so you would combine both of these into : 

  Dim firstNames = YourCollection.Where(Function (f) f.FirstName = "First").ToList() 
  Dim emailAddresses = YourCollection.DistinctBy(Function (f) f.Email).ToList()
  
  'Build your final collection by storing both results in a single collection'
  Dim collection = firstNames.AddRange(emailAddresses)
  

  If you wanted to perform an actual JOIN, you would likely want to the available Join() method through LINQ.

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  Bosen Tom

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  Re: Combine two list(of T) collections to contain distict objects

  Dec 17, 2013 03:22 AM|Bosen Tom|LINK

  Imports System
  Imports System.Collections.Generic
  Class Example
      Public Shared Sub Main()
          Try 
  
              Dim boxEqC As New BoxEqualityComparer()
  
              Dim boxes As Dictionary(Of Box, [String]) = _
                          New Dictionary(Of Box, String)(boxEqC)
  
              Dim redBox As New Box(4, 3, 4)
              Dim blueBox As New Box(4, 3, 4)
  
              boxes.Add(redBox, "red")
              boxes.Add(blueBox, "blue")
  
          Catch argEx As ArgumentException
              Console.WriteLine(argEx.Message)
          End Try 
      End Sub 
  End Class 
  
  Public Class Box
      Public Sub New(ByVal h As Integer, ByVal l As Integer, _
                                          ByVal w As Integer)
          Me.Height = h
          Me.Length = l
          Me.Width = w
      End Sub 
      Private _Height As Integer 
      Public Property Height() As Integer 
          Get 
              Return _Height
          End Get 
          Set(ByVal value As Integer)
              _Height = value
          End Set 
      End Property 
      Private _Length As Integer 
      Public Property Length() As Integer 
          Get 
              Return _Length
          End Get 
          Set(ByVal value As Integer)
              _Length = value
          End Set 
      End Property 
      Private _Width As Integer 
      Public Property Width() As Integer 
          Get 
              Return _Width
          End Get 
          Set(ByVal value As Integer)
              _Width = value
          End Set 
      End Property 
  End Class 
  
  
  Class BoxEqualityComparer
      Implements IEqualityComparer(Of Box)
  
      Public Overloads Function Equals(ByVal b1 As Box, ByVal b2 As Box) _
                     As Boolean Implements IEqualityComparer(Of Box).Equals
  
          If b1.Height = b2.Height And b1.Length = _
                  b2.Length And b1.Width = b2.Width Then 
              Return True 
          Else 
              Return False 
          End If 
      End Function 
  
  
      Public Overloads Function GetHashCode(ByVal bx As Box) _
                  As Integer Implements IEqualityComparer(Of Box).GetHashCode
          Dim hCode As Integer = bx.Height Xor bx.Length Xor bx.Width
          Return hCode.GetHashCode()
      End Function 
  
  End Class

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  peterthegrea...

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  Re: Combine two list(of T) collections to contain distict objects

  Dec 29, 2013 04:28 PM|peterthegreat|LINK

  pr = From p In product.Values Group p.Price By Key = p.Email Into Group = Group _
                    Select New With {.Email = Key, .Price = Group.Sum()}

  i have been working with a linq query like this.

  i have another custom list collection  list(of product)

  i want to find the product that match on email property without   enumerating pr ?

   i use linq here because it is convenient for sum the Price into groups (Email)

    

  
   

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  peterthegrea...

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  Re: Combine two list(of T) collections to contain distict objects

  Dec 31, 2013 03:24 PM|peterthegreat|LINK

  is this the method used for comparing custom type objects ?

  and not those given previous ?

  Thanks