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

May 09, 2021 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 C#.

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.Extensions.Partition‘ to group an integer array.





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

using Utils;

// Declare array of integers 
var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };

// Split array into sub groups
var numbersPartition = numbers.Partition(3);

// Display grouped batches
for (var batchCount = 0; batchCount < numbersPartition.Count; ++batchCount) {
    var batch = numbersPartition[batchCount];

    Console.WriteLine($"Batch #{batchCount + 1}");
    foreach (var item in batch) {
        Console.WriteLine($"  Item: {item}");
    }
}

// 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
 
using Utils;
 
// Declare array of integers 
var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
 
// Split array into sub groups
var numbersPartition = numbers.Partition(3);
 
// Display grouped batches
for (var batchCount = 0; batchCount < numbersPartition.Count; ++batchCount) {
    var batch = numbersPartition[batchCount];
 
    Console.WriteLine($"Batch #{batchCount + 1}");
    foreach (var item in batch) {
        Console.WriteLine($"  Item: {item}");
    }
}
 
// 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.Extensions.Partition‘ to group a list of strings.





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

using Utils;

// Declare list of strings
var names = new List<string>() {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
};

// Split array into sub groups
var namesPartition = names.Partition(2);

// Display grouped batches
for (var batchCount = 0; batchCount < namesPartition.Count; ++batchCount) {
    var batch = namesPartition[batchCount];

    Console.WriteLine($"Batch #{batchCount + 1}");
    foreach (var item in batch) {
        Console.WriteLine($"  Item: {item}");
    }
}

// expected output:
/*
    Batch #1
      Item: Kenneth
      Item: Jennifer
    Batch #2
      Item: Lynn
      Item: Sole
*/
			
				
					
				
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						// Partition - String List
 
using Utils;
 
// Declare list of strings
var names = new List<string>() {
    "Kenneth",
    "Jennifer",
    "Lynn",
    "Sole"
};
 
// Split array into sub groups
var namesPartition = names.Partition(2);
 
// Display grouped batches
for (var batchCount = 0; batchCount < namesPartition.Count; ++batchCount) {
    var batch = namesPartition[batchCount];
 
    Console.WriteLine($"Batch #{batchCount + 1}");
    foreach (var item in batch) {
        Console.WriteLine($"  Item: {item}");
    }
}
 
// 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.Extensions.Partition‘ to group a list of custom objects.





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

using Utils;

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

// Declare list of objects
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
    }
};

// Split array into sub groups
var partsPartition = parts.Partition(4);

// Display grouped batches
for (var batchCount = 0; batchCount < partsPartition.Count; ++batchCount) {
    var batch = partsPartition[batchCount];

    Console.WriteLine($"Batch #{batchCount + 1}");
    foreach (var item in batch) {
        Console.WriteLine($"  Item: {item.PartId} - {item.PartName}");
    }
}

// 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
 
using Utils;
 
public class Part {
    public string PartName { get; set; }
    public int PartId { get; set; }
}
 
// Declare list of objects
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
    }
};
 
// Split array into sub groups
var partsPartition = parts.Partition(4);
 
// Display grouped batches
for (var batchCount = 0; batchCount < partsPartition.Count; ++batchCount) {
    var batch = partsPartition[batchCount];
 
    Console.WriteLine($"Batch #{batchCount + 1}");
    foreach (var item in batch) {
        Console.WriteLine($"  Item: {item.PartId} - {item.PartName}");
    }
}
 
// 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
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 9, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.cs
//    Description: Handles general utility functions
// ============================================================================
using System;
using System.Collections.Generic;

namespace Utils {
    public static class Extensions {
        /// <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>
        public static List<List<T>> Partition<T>(this IEnumerable<T> source, int size) {
            var result = new List<List<T>>();
            List<T> batch = null;
            int index = 0;
            foreach (var item in source) {
                if (index % size == 0) {
                    batch = new List<T>();
                    result.Add(batch);
                }
                batch.Add(item);
                ++index;
            }
            return result;
        }
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 9, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.cs
//    Description: Handles general utility functions
// ============================================================================
using System;
using System.Collections.Generic;
 
namespace Utils {
    public static class Extensions {
        /// <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>
        public static List<List<T>> Partition<T>(this IEnumerable<T> source, int size) {
            var result = new List<List<T>>();
            List<T> batch = null;
            int index = 0;
            foreach (var item in source) {
                if (index % size == 0) {
                    batch = new List<T>();
                    result.Add(batch);
                }
                batch.Add(item);
                ++index;
            }
            return result;
        }
    }
}// 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 9, 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 {
            // Declare array of integers 
            var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };

            // Split array into sub groups
            var numbersPartition = numbers.Partition(3);

            // Display grouped batches
            for (var batchCount = 0; batchCount < numbersPartition.Count; ++batchCount) {
                var batch = numbersPartition[batchCount];

                Display($"Batch #{batchCount + 1}");
                foreach (var item in batch) {
                    Display($"  Item: {item}");
                }
            }

            Display("");

            // Declare list of strings
            var names = new List<string>() {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            };

            // Split array into sub groups
            var namesPartition = names.Partition(2);

            // Display grouped batches
            for (var batchCount = 0; batchCount < namesPartition.Count; ++batchCount) {
                var batch = namesPartition[batchCount];

                Display($"Batch #{batchCount + 1}");
                foreach (var item in batch) {
                    Display($"  Item: {item}");
                }
            }

            Display("");

            // Declare list of objects
            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
                }
            };

            // Split array into sub groups
            var partsPartition = parts.Partition(4);

            // Display grouped batches
            for (var batchCount = 0; batchCount < partsPartition.Count; ++batchCount) {
                var batch = partsPartition[batchCount];

                Display($"Batch #{batchCount + 1}");
                foreach (var item in batch) {
                    Display($"  Item: {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 9, 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 {
            // Declare array of integers 
            var numbers = new int[] { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
 
            // Split array into sub groups
            var numbersPartition = numbers.Partition(3);
 
            // Display grouped batches
            for (var batchCount = 0; batchCount < numbersPartition.Count; ++batchCount) {
                var batch = numbersPartition[batchCount];
 
                Display($"Batch #{batchCount + 1}");
                foreach (var item in batch) {
                    Display($"  Item: {item}");
                }
            }
 
            Display("");
 
            // Declare list of strings
            var names = new List<string>() {
                "Kenneth",
                "Jennifer",
                "Lynn",
                "Sole"
            };
 
            // Split array into sub groups
            var namesPartition = names.Partition(2);
 
            // Display grouped batches
            for (var batchCount = 0; batchCount < namesPartition.Count; ++batchCount) {
                var batch = namesPartition[batchCount];
 
                Display($"Batch #{batchCount + 1}");
                foreach (var item in batch) {
                    Display($"  Item: {item}");
                }
            }
 
            Display("");
 
            // Declare list of objects
            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
                }
            };
 
            // Split array into sub groups
            var partsPartition = parts.Partition(4);
 
            // Display grouped batches
            for (var batchCount = 0; batchCount < partsPartition.Count; ++batchCount) {
                var batch = partsPartition[batchCount];
 
                Display($"Batch #{batchCount + 1}");
                foreach (var item in batch) {
                    Display($"  Item: {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, split list

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

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