C# || How To Shuffle & Randomize An Array/List/IEnumerable Using C#

May 07, 2021 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 C#.

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.Extensions.Shuffle‘ to randomize an integer array.





		
		
			1. Shuffle - Integer Array
			
C#
			
			// Shuffle - Integer Array

using Utils;

var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
var results = numbers.Shuffle();

foreach (var item in results) {
    Console.WriteLine($"{item}");
}

// example output:
/*
    1991
    1987
    2009
    22
    28
    2019
    31
    19
*/
			
				
					
				
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						// Shuffle - Integer Array
 
using Utils;
 
var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
var results = numbers.Shuffle();
 
foreach (var item in results) {
    Console.WriteLine($"{item}");
}
 
// example output:
/*
    1991
    1987
    2009
    22
    28
    2019
    31
    19
*/

2. Shuffle – String List

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





		
		
			2. Shuffle - String List
			
C#
			
			// Shuffle - String List

using Utils;

var names = new List<string>() {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
};

var results = names.Shuffle();

foreach (var item in results) {
    Console.WriteLine($"{item}");
}

// example output:
/*
    Jennifer
    Kenneth
    Sole
    Lynn
*/
			
				
					
				
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						// Shuffle - String List
 
using Utils;
 
var names = new List<string>() {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
};
 
var results = names.Shuffle();
 
foreach (var item in results) {
    Console.WriteLine($"{item}");
}
 
// example output:
/*
    Jennifer
    Kenneth
    Sole
    Lynn
*/

3. Shuffle – Custom Object List

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





		
		
			3. Shuffle - Custom Object List
			
C#
			
			// Shuffle - Custom Object List

using Utils;

public class Part {
    public string PartName { get; set; }
    public int PartId { get; set; }
}

var parts = new List<Part>() {
    new Part() {
        PartName = "crank arm",
        PartId = 1234
    },
    new Part() {
        PartName = "chain ring",
        PartId = 1334
    },
    new Part() {
        PartName = "regular seat",
        PartId = 1434
    },
    new Part() {
        PartName = "banana seat",
        PartId = 1444
    },
    new Part() {
        PartName = "cassette",
        PartId = 1534
    },
    new Part() {
        PartName = "shift lever",
        PartId = 1634
    }
};

var results = parts.Shuffle();

foreach (var item in results) {
    Console.WriteLine($"{item.PartId} - {item.PartName}");
}  

// example output:
/*
    1334 - chain ring
    1444 - banana seat
    1434 - regular seat
    1534 - cassette
    1634 - shift lever
    1234 - crank arm
*/
			
				
					
				
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						// Shuffle - Custom Object List
 
using Utils;
 
public class Part {
    public string PartName { get; set; }
    public int PartId { get; set; }
}
 
var parts = new List<Part>() {
    new Part() {
        PartName = "crank arm",
        PartId = 1234
    },
    new Part() {
        PartName = "chain ring",
        PartId = 1334
    },
    new Part() {
        PartName = "regular seat",
        PartId = 1434
    },
    new Part() {
        PartName = "banana seat",
        PartId = 1444
    },
    new Part() {
        PartName = "cassette",
        PartId = 1534
    },
    new Part() {
        PartName = "shift lever",
        PartId = 1634
    }
};
 
var results = parts.Shuffle();
 
foreach (var item in results) {
    Console.WriteLine($"{item.PartId} - {item.PartName}");
}  
 
// example output:
/*
    1334 - chain ring
    1444 - banana seat
    1434 - regular seat
    1534 - cassette
    1634 - shift lever
    1234 - crank arm
*/

4. Utils Namespace

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





		
		
			Utils Namespace
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 7, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.cs
//    Description: Handles general utility functions
// ============================================================================
using System;
using System.Linq;
using System.Collections.Generic;

namespace Utils {
    public static class Extensions {
        /// <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>
        public static List<T> Shuffle<T>(this IEnumerable<T> list) {
            var r = new Random();
            var shuffled = list.ToList();
            for (int index = 0; index < shuffled.Count; ++index) {
                var randomIndex = r.Next(index, shuffled.Count);
                if (index != randomIndex) {
                    var temp = shuffled[index];
                    shuffled[index] = shuffled[randomIndex];
                    shuffled[randomIndex] = temp;
                }
            }
            return shuffled;
        }
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 7, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.cs
//    Description: Handles general utility functions
// ============================================================================
using System;
using System.Linq;
using System.Collections.Generic;
 
namespace Utils {
    public static class Extensions {
        /// <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>
        public static List<T> Shuffle<T>(this IEnumerable<T> list) {
            var r = new Random();
            var shuffled = list.ToList();
            for (int index = 0; index < shuffled.Count; ++index) {
                var randomIndex = r.Next(index, shuffled.Count);
                if (index != randomIndex) {
                    var temp = shuffled[index];
                    shuffled[index] = shuffled[randomIndex];
                    shuffled[randomIndex] = temp;
                }
            }
            return shuffled;
        }
    }
}// 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
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 7, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Program.cs
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
using System;
using System.Diagnostics;
using System.Collections.Generic;
using Utils;

public class Program {

    public class Part {
        public string PartName { get; set; }
        public int PartId { get; set; }
    }

    static void Main(string[] args) {
        try {
            var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
            var results = numbers.Shuffle();

            foreach (var item in results) {
                Display($"{item}");
            }
             
            Display("");

            var names = new List<string>() {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            };

            var results1 = names.Shuffle();

            foreach (var item in results1) {
                Display($"{item}");
            }

            Display("");

            var parts = new List<Part>() {
                new Part() {
                    PartName = "crank arm",
                    PartId = 1234
                },
                new Part() {
                    PartName = "chain ring",
                    PartId = 1334
                },
                new Part() {
                    PartName = "regular seat",
                    PartId = 1434
                },
                new Part() {
                    PartName = "banana seat",
                    PartId = 1444
                },
                new Part() {
                    PartName = "cassette",
                    PartId = 1534
                },
                new Part() {
                    PartName = "shift lever",
                    PartId = 1634
                }
            };

            var results2 = parts.Shuffle();

            foreach (var item in results2) {
                Display($"{item.PartId} - {item.PartName}");
            } 
        } catch (Exception ex) {
            Display(ex.ToString());
        } finally {
            Console.ReadLine();
        }
    }

    static void Display(string message) {
        Console.WriteLine(message);
        Debug.Print(message);
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 7, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Program.cs
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
using System;
using System.Diagnostics;
using System.Collections.Generic;
using Utils;
 
public class Program {
 
    public class Part {
        public string PartName { get; set; }
        public int PartId { get; set; }
    }
 
    static void Main(string[] args) {
        try {
            var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
            var results = numbers.Shuffle();
 
            foreach (var item in results) {
                Display($"{item}");
            }
             
            Display("");
 
            var names = new List<string>() {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            };
 
            var results1 = names.Shuffle();
 
            foreach (var item in results1) {
                Display($"{item}");
            }
 
            Display("");
 
            var parts = new List<Part>() {
                new Part() {
                    PartName = "crank arm",
                    PartId = 1234
                },
                new Part() {
                    PartName = "chain ring",
                    PartId = 1334
                },
                new Part() {
                    PartName = "regular seat",
                    PartId = 1434
                },
                new Part() {
                    PartName = "banana seat",
                    PartId = 1444
                },
                new Part() {
                    PartName = "cassette",
                    PartId = 1534
                },
                new Part() {
                    PartName = "shift lever",
                    PartId = 1634
                }
            };
 
            var results2 = parts.Shuffle();
 
            foreach (var item in results2) {
                Display($"{item.PartId} - {item.PartName}");
            } 
        } catch (Exception ex) {
            Display(ex.ToString());
        } finally {
            Console.ReadLine();
        }
    }
 
    static void Display(string message) {
        Console.WriteLine(message);
        Debug.Print(message);
    }
}// 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: C#, Console Tags: c-sharp, shuffle

C# || How To Shuffle & Randomize An Array/List/IEnumerable Using C#

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