VB.NET || How To Split & Batch An Array/List/IEnumerable Into Smaller Sub-Lists Of N Size Using VB.NET

November 15, 2020 admin No comments

The following is a module with functions which demonstrates how to split/batch an Array/List/IEnumerable into smaller sublists of n size using VB.NET.

This generic extension function uses a simple for loop to group items into batches.

1. Partition – Integer Array

The example below demonstrates the use of ‘Utils.Partition‘ to group an integer array.





		
		
			1. Partition - Integer Array
			
Visual Basic .NET
			
			' Partition - Integer Array

Imports Utils

' Declare array of integers 
Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}

' Split array into sub groups
Dim numbersPartition = numbers.Partition(3)

' Display grouped batches
For batchCount = 0 To numbersPartition.Count - 1
    Dim batch = numbersPartition(batchCount)

    Debug.Print($"Batch #{batchCount + 1}")
    For Each item In batch
        Debug.Print($"  Item: {item}")
    Next
Next

' expected output:
'    Batch #1
'      Item: 1987
'      Item: 19
'      Item: 22
'    Batch #2
'      Item: 2009
'      Item: 2019
'      Item: 1991
'    Batch #3
'      Item: 28
'      Item: 31
			
				
					
				
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						' Partition - Integer Array
 
Imports Utils
 
' Declare array of integers 
Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}
 
' Split array into sub groups
Dim numbersPartition = numbers.Partition(3)
 
' Display grouped batches
For batchCount = 0 To numbersPartition.Count - 1
    Dim batch = numbersPartition(batchCount)
 
    Debug.Print($"Batch #{batchCount + 1}")
    For Each item In batch
        Debug.Print($"  Item: {item}")
    Next
Next
 
' expected output:
'    Batch #1
'      Item: 1987
'      Item: 19
'      Item: 22
'    Batch #2
'      Item: 2009
'      Item: 2019
'      Item: 1991
'    Batch #3
'      Item: 28
'      Item: 31

2. Partition – String List

The example below demonstrates the use of ‘Utils.Partition‘ to group a list of strings.





		
		
			2. Partition - String List
			
Visual Basic .NET
			
			' Partition - String List

Imports Utils

' Declare list of strings
Dim names = New List(Of String) From {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
}

' Split array into sub groups
Dim namesPartition = names.Partition(2)

' Display grouped batches
For batchCount = 0 To namesPartition.Count - 1
    Dim batch = namesPartition(batchCount)

    Debug.Print($"Batch #{batchCount + 1}")
    For Each item In batch
        Debug.Print($"  Item: {item}")
    Next
Next

' expected output:
'    Batch #1
'      Item: Kenneth
'      Item: Jennifer
'    Batch #2
'      Item: Lynn
'      Item: Sole
			
				
					
				
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						' Partition - String List
 
Imports Utils
 
' Declare list of strings
Dim names = New List(Of String) From {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
}
 
' Split array into sub groups
Dim namesPartition = names.Partition(2)
 
' Display grouped batches
For batchCount = 0 To namesPartition.Count - 1
    Dim batch = namesPartition(batchCount)
 
    Debug.Print($"Batch #{batchCount + 1}")
    For Each item In batch
        Debug.Print($"  Item: {item}")
    Next
Next
 
' expected output:
'    Batch #1
'      Item: Kenneth
'      Item: Jennifer
'    Batch #2
'      Item: Lynn
'      Item: Sole

3. Partition – Custom Object List

The example below demonstrates the use of ‘Utils.Partition‘ to group a list of custom objects.





		
		
			3. Partition - Custom Object List
			
Visual Basic .NET
			
			' Partition - Custom Object List

Imports Utils

Public Class Part
    Public Property PartName As String
    Public Property PartId As Integer
End Class

' Declare list of objects
Dim parts = New List(Of Part) From {
    New Part With {
     .PartName = "crank arm",
     .PartId = 1234
},
    New Part With {
     .PartName = "chain ring",
     .PartId = 1334
},
    New Part With {
     .PartName = "regular seat",
     .PartId = 1434
},
    New Part With {
     .PartName = "banana seat",
     .PartId = 1444
},
    New Part With {
     .PartName = "cassette",
     .PartId = 1534
},
    New Part With {
     .PartName = "shift lever",
     .PartId = 1634
}}

' Split array into sub groups
Dim partsPartition = parts.Partition(4)

' Display grouped batches
For batchCount = 0 To partsPartition.Count - 1
    Dim batch = partsPartition(batchCount)

    Debug.Print($"Batch #{batchCount + 1}")
    For Each item In batch
        Debug.Print($"  Item: {item.PartId} - {item.PartName}")
    Next
Next

' expected output:
'    Batch #1
'      Item: 1234 - crank arm
'      Item: 1334 - chain ring
'      Item: 1434 - regular seat
'      Item: 1444 - banana seat
'    Batch #2
'      Item: 1534 - cassette
'      Item: 1634 - shift lever
			
				
					
				
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						' Partition - Custom Object List
 
Imports Utils
 
Public Class Part
    Public Property PartName As String
    Public Property PartId As Integer
End Class
 
' Declare list of objects
Dim parts = New List(Of Part) From {
    New Part With {
     .PartName = "crank arm",
     .PartId = 1234
},
    New Part With {
     .PartName = "chain ring",
     .PartId = 1334
},
    New Part With {
     .PartName = "regular seat",
     .PartId = 1434
},
    New Part With {
     .PartName = "banana seat",
     .PartId = 1444
},
    New Part With {
     .PartName = "cassette",
     .PartId = 1534
},
    New Part With {
     .PartName = "shift lever",
     .PartId = 1634
}}
 
' Split array into sub groups
Dim partsPartition = parts.Partition(4)
 
' Display grouped batches
For batchCount = 0 To partsPartition.Count - 1
    Dim batch = partsPartition(batchCount)
 
    Debug.Print($"Batch #{batchCount + 1}")
    For Each item In batch
        Debug.Print($"  Item: {item.PartId} - {item.PartName}")
    Next
Next
 
' expected output:
'    Batch #1
'      Item: 1234 - crank arm
'      Item: 1334 - chain ring
'      Item: 1434 - regular seat
'      Item: 1444 - banana seat
'    Batch #2
'      Item: 1534 - cassette
'      Item: 1634 - shift lever

4. Utils Namespace

The following is the Utils Namespace. Include this in your project to start using!





		
		
			Utils Namespace
			
Visual Basic .NET
			
			' ============================================================================
'    Author: Kenneth Perkins
'    Date:   Nov 15, 2020
'    Taken From: http://programmingnotes.org/
'    File: Utils.vb
'    Description: Handles general utility functions
' ============================================================================
Option Strict On
Option Explicit On

Namespace Global.Utils
    Public Module modUtils
        ''' <summary>
        ''' Breaks a list into smaller sub-lists of a specified size
        ''' </summary>
        ''' <param name="source">An IEnumerable to split into smaller sub-lists</param> 
        ''' <param name="size">The maximum size of each sub-list</param> 
        ''' <returns>The smaller sub-lists of the specified size</returns>
        <Runtime.CompilerServices.Extension()>
        Public Function Partition(Of T)(source As IEnumerable(Of T), size As Integer) As List(Of List(Of T))
            Dim result = New List(Of List(Of T))
            Dim batch As List(Of T) = Nothing
            For index = 0 To source.Count - 1
                If index Mod size = 0 Then
                    batch = New List(Of T)
                    result.Add(batch)
                End If
                batch.Add(source(index))
            Next
            Return result
        End Function
    End Module
End Namespace ' http://programmingnotes.org/
			
				
					
				
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						' ============================================================================
'    Author: Kenneth Perkins
'    Date:   Nov 15, 2020
'    Taken From: http://programmingnotes.org/
'    File: Utils.vb
'    Description: Handles general utility functions
' ============================================================================
Option Strict On
Option Explicit On
 
Namespace Global.Utils
    Public Module modUtils
        ''' <summary>
        ''' Breaks a list into smaller sub-lists of a specified size
        ''' </summary>
        ''' <param name="source">An IEnumerable to split into smaller sub-lists</param> 
        ''' <param name="size">The maximum size of each sub-list</param> 
        ''' <returns>The smaller sub-lists of the specified size</returns>
        <Runtime.CompilerServices.Extension()>
        Public Function Partition(Of T)(source As IEnumerable(Of T), size As Integer) As List(Of List(Of T))
            Dim result = New List(Of List(Of T))
            Dim batch As List(Of T) = Nothing
            For index = 0 To source.Count - 1
                If index Mod size = 0 Then
                    batch = New List(Of T)
                    result.Add(batch)
                End If
                batch.Add(source(index))
            Next
            Return result
        End Function
    End Module
End Namespace ' http://programmingnotes.org/

5. More Examples

Below are more examples demonstrating the use of the ‘Utils‘ Namespace. Don’t forget to include the module when running the examples!





		
		
			More Examples
			
Visual Basic .NET
			
			' ============================================================================
'    Author: Kenneth Perkins
'    Date:   Nov 15, 2020
'    Taken From: http://programmingnotes.org/
'    File: Program.vb
'    Description: The following demonstrates the use of the Utils Namespace
' ============================================================================
Option Strict On
Option Explicit On
Imports System
Imports Utils

Public Module Program

    Public Class Part
        Public Property PartName As String
        Public Property PartId As Integer
    End Class

    Sub Main(args As String())
        Try
            ' Declare array of integers 
            Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}

            ' Split array into sub groups
            Dim numbersPartition = numbers.Partition(3)

            ' Display grouped batches
            For batchCount = 0 To numbersPartition.Count - 1
                Dim batch = numbersPartition(batchCount)
                Display($"Batch #{batchCount + 1}")
                For Each item In batch
                    Display($"  Item: {item}")
                Next
            Next

            Display("")

            ' Declare list of strings
            Dim names = New List(Of String) From {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            }

            ' Split array into sub groups
            Dim namesPartition = names.Partition(2)

            ' Display grouped batches
            For batchCount = 0 To namesPartition.Count - 1
                Dim batch = namesPartition(batchCount)
                Display($"Batch #{batchCount + 1}")
                For Each item In batch
                    Display($"  Item: {item}")
                Next
            Next

            Display("")

            ' Declare list of objects
            Dim parts = New List(Of Part) From {
                New Part With {
                 .PartName = "crank arm",
                 .PartId = 1234
            },
                New Part With {
                 .PartName = "chain ring",
                 .PartId = 1334
            },
                New Part With {
                 .PartName = "regular seat",
                 .PartId = 1434
            },
                New Part With {
                 .PartName = "banana seat",
                 .PartId = 1444
            },
                New Part With {
                 .PartName = "cassette",
                 .PartId = 1534
            },
                New Part With {
                 .PartName = "shift lever",
                 .PartId = 1634
            }}

            ' Split array into sub groups
            Dim partsPartition = parts.Partition(4)

            ' Display grouped batches
            For batchCount = 0 To partsPartition.Count - 1
                Dim batch = partsPartition(batchCount)
                Display($"Batch #{batchCount + 1}")
                For Each item In batch
                    Display($"  Item: {item.PartId} - {item.PartName}")
                Next
            Next
        Catch ex As Exception
            Display(ex.ToString)
        Finally
            Console.ReadLine()
        End Try
    End Sub

    Public Sub Display(message As String)
        Console.WriteLine(message)
        Debug.Print(message)
    End Sub
End Module ' http://programmingnotes.org/
			
				
					
				
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						' ============================================================================
'    Author: Kenneth Perkins
'    Date:   Nov 15, 2020
'    Taken From: http://programmingnotes.org/
'    File: Program.vb
'    Description: The following demonstrates the use of the Utils Namespace
' ============================================================================
Option Strict On
Option Explicit On
Imports System
Imports Utils
 
Public Module Program
 
    Public Class Part
        Public Property PartName As String
        Public Property PartId As Integer
    End Class
 
    Sub Main(args As String())
        Try
            ' Declare array of integers 
            Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}
 
            ' Split array into sub groups
            Dim numbersPartition = numbers.Partition(3)
 
            ' Display grouped batches
            For batchCount = 0 To numbersPartition.Count - 1
                Dim batch = numbersPartition(batchCount)
                Display($"Batch #{batchCount + 1}")
                For Each item In batch
                    Display($"  Item: {item}")
                Next
            Next
 
            Display("")
 
            ' Declare list of strings
            Dim names = New List(Of String) From {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            }
 
            ' Split array into sub groups
            Dim namesPartition = names.Partition(2)
 
            ' Display grouped batches
            For batchCount = 0 To namesPartition.Count - 1
                Dim batch = namesPartition(batchCount)
                Display($"Batch #{batchCount + 1}")
                For Each item In batch
                    Display($"  Item: {item}")
                Next
            Next
 
            Display("")
 
            ' Declare list of objects
            Dim parts = New List(Of Part) From {
                New Part With {
                 .PartName = "crank arm",
                 .PartId = 1234
            },
                New Part With {
                 .PartName = "chain ring",
                 .PartId = 1334
            },
                New Part With {
                 .PartName = "regular seat",
                 .PartId = 1434
            },
                New Part With {
                 .PartName = "banana seat",
                 .PartId = 1444
            },
                New Part With {
                 .PartName = "cassette",
                 .PartId = 1534
            },
                New Part With {
                 .PartName = "shift lever",
                 .PartId = 1634
            }}
 
            ' Split array into sub groups
            Dim partsPartition = parts.Partition(4)
 
            ' Display grouped batches
            For batchCount = 0 To partsPartition.Count - 1
                Dim batch = partsPartition(batchCount)
                Display($"Batch #{batchCount + 1}")
                For Each item In batch
                    Display($"  Item: {item.PartId} - {item.PartName}")
                Next
            Next
        Catch ex As Exception
            Display(ex.ToString)
        Finally
            Console.ReadLine()
        End Try
    End Sub
 
    Public Sub Display(message As String)
        Console.WriteLine(message)
        Debug.Print(message)
    End Sub
End Module ' http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

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Posted in: Console, VB.NET Tags: split list, vb.net

VB.NET || How To Split & Batch An Array/List/IEnumerable Into Smaller Sub-Lists Of N Size Using VB.NET

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