VB.NET || How To Shuffle & Randomize An Array/List/IEnumerable Using VB.NET

November 03, 2020 admin No comments

The following is a module with functions which demonstrates how to randomize and shuffle the contents of an Array/List/IEnumerable using VB.NET.

This function shuffles an IEnumerable and returns the results as a new List(Of T).

This function is generic, so it should work on IEnumerables of any datatype.

1. Shuffle – Integer Array

The example below demonstrates the use of ‘Utils.Shuffle‘ to randomize an integer array.





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

Imports Utils

Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}
Dim results = numbers.Shuffle

For Each item In results
    Debug.Print($"{item}")
Next

' example output:
'    2009
'    1987
'    31
'    22
'    28
'    2019
'    1991
'    19
			
				
					
				
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						' Shuffle - Integer Array
 
Imports Utils
 
Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}
Dim results = numbers.Shuffle
 
For Each item In results
    Debug.Print($"{item}")
Next
 
' example output:
'    2009
'    1987
'    31
'    22
'    28
'    2019
'    1991
'    19

2. Shuffle – String List

The example below demonstrates the use of ‘Utils.Shuffle‘ to randomize a list of strings.





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

Imports Utils

Dim names = New List(Of String) From {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
}

Dim results = names.Shuffle

For Each item In results
    Debug.Print($"{item}")
Next

' example output:
'    Sole
'    Kenneth
'    Lynn
'    Jennifer
			
				
					
				
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						' Shuffle - String List
 
Imports Utils
 
Dim names = New List(Of String) From {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
}
 
Dim results = names.Shuffle
 
For Each item In results
    Debug.Print($"{item}")
Next
 
' example output:
'    Sole
'    Kenneth
'    Lynn
'    Jennifer

3. Shuffle – Custom Object List

The example below demonstrates the use of ‘Utils.Shuffle‘ to randomize a list of custom objects.





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

Imports Utils

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

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
}}

Dim results = parts.Shuffle

For Each item In results
    Debug.Print($"{item.PartId} {item.PartName}")
Next

' example output:
'    1634 shift lever
'    1444 banana seat
'    1434 regular seat
'    1234 crank arm
'    1334 chain ring
'    1534 cassette
			
				
					
				
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						' Shuffle - Custom Object List
 
Imports Utils
 
Public Class Part
    Public Property PartName As String
    Public Property PartId As Integer
End Class
 
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
}}
 
Dim results = parts.Shuffle
 
For Each item In results
    Debug.Print($"{item.PartId} {item.PartName}")
Next
 
' example output:
'    1634 shift lever
'    1444 banana seat
'    1434 regular seat
'    1234 crank arm
'    1334 chain ring
'    1534 cassette

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 3, 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>
        ''' Shuffles an IEnumerable and returns the results as a List
        ''' </summary>
        ''' <param name="list">The IEnumerable list to shuffle</param>
        ''' <returns>A List of shuffled items from the IEnumerable</returns>
        <Runtime.CompilerServices.Extension()>
        Function Shuffle(Of T)(list As IEnumerable(Of T)) As List(Of T)
            Dim r = New Random
            Dim shuffled = list.ToList
            For index = 0 To shuffled.Count - 1
                Dim randomIndex = r.Next(index, shuffled.Count)
                If index <> randomIndex Then
                    Dim temp = shuffled(index)
                    shuffled(index) = shuffled(randomIndex)
                    shuffled(randomIndex) = temp
                End If
            Next
            Return shuffled
        End Function
    End Module
End Namespace ' http://programmingnotes.org/
			
				
					
				
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						' ============================================================================
'    Author: Kenneth Perkins
'    Date:   Nov 3, 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>
        ''' Shuffles an IEnumerable and returns the results as a List
        ''' </summary>
        ''' <param name="list">The IEnumerable list to shuffle</param>
        ''' <returns>A List of shuffled items from the IEnumerable</returns>
        <Runtime.CompilerServices.Extension()>
        Function Shuffle(Of T)(list As IEnumerable(Of T)) As List(Of T)
            Dim r = New Random
            Dim shuffled = list.ToList
            For index = 0 To shuffled.Count - 1
                Dim randomIndex = r.Next(index, shuffled.Count)
                If index <> randomIndex Then
                    Dim temp = shuffled(index)
                    shuffled(index) = shuffled(randomIndex)
                    shuffled(randomIndex) = temp
                End If
            Next
            Return shuffled
        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 3, 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

Module Program

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

    Sub Main(args As String())
        Try
            Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}
            Dim results = numbers.Shuffle

            For Each item In results
                Display($"{item}")
            Next

            Display("")

            Dim names = New List(Of String) From {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            }

            Dim results1 = names.Shuffle

            For Each item In results1
                Display($"{item}")
            Next

            Display("")

            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
            }}

            Dim results2 = parts.Shuffle

            For Each item In results2
                Display($"{item.PartId} {item.PartName}")
            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 3, 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
 
Module Program
 
    Public Class Part
        Public Property PartName As String
        Public Property PartId As Integer
    End Class
 
    Sub Main(args As String())
        Try
            Dim numbers = New Integer() {1987, 19, 22, 2009, 2019, 1991, 28, 31}
            Dim results = numbers.Shuffle
 
            For Each item In results
                Display($"{item}")
            Next
 
            Display("")
 
            Dim names = New List(Of String) From {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            }
 
            Dim results1 = names.Shuffle
 
            For Each item In results1
                Display($"{item}")
            Next
 
            Display("")
 
            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
            }}
 
            Dim results2 = parts.Shuffle
 
            For Each item In results2
                Display($"{item.PartId} {item.PartName}")
            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: shuffle, vb.net

VB.NET || How To Shuffle & Randomize An Array/List/IEnumerable Using VB.NET

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