How to get a dimension (slice) from a multidimensional array

Question

I'm trying to figure out how to get a single dimension from a multidimensional array (for the sake of argument, let's say it's 2D), I have a multidimensional array:

double[,] d = new double[,] { { 1, 2, 3, 4, 5 }, { 5, 4, 3, 2, 1 } }; 

If it was a jagged array, I would simply call d[0] and that would give me an array of {1, 2, 3, 4, 5}, is there a way I can achieve the same with a 2D array?

Answer 1

No. You could of course write a wrapper class that represents a slice, and has an indexer internally - but nothing inbuilt. The other approach would be to write a method that makes a copy of a slice and hands back a vector - it depends whether you want a copy or not.

using System; static class ArraySliceExt {     public static ArraySlice2D<T> Slice<T>(this T[,] arr, int firstDimension)     {         return new ArraySlice2D<T>(arr, firstDimension);     } } class ArraySlice2D<T> {     private readonly T[,] arr;     private readonly int firstDimension;     private readonly int length;     public int Length { get { return length; } }     public ArraySlice2D(T[,] arr, int firstDimension)     {         this.arr = arr;         this.firstDimension = firstDimension;         this.length = arr.GetUpperBound(1) + 1;     }     public T this[int index]     {         get { return arr[firstDimension, index]; }         set { arr[firstDimension, index] = value; }     } } public static class Program {     static void Main()     {         double[,] d = new double[,] { { 1, 2, 3, 4, 5 }, { 5, 4, 3, 2, 1 } };         var slice = d.Slice(0);         for (int i = 0; i < slice.Length; i++)         {             Console.WriteLine(slice[i]);         }     } } 

Answer 2

Improved version of that answer:

public static IEnumerable<T> SliceRow<T>(this T[,] array, int row) {     for (var i = array.GetLowerBound(1); i <= array.GetUpperBound(1); i++)     {         yield return array[row, i];     } }  public static IEnumerable<T> SliceColumn<T>(this T[,] array, int column) {     for (var i = array.GetLowerBound(0); i <= array.GetUpperBound(0); i++)     {         yield return array[i, column];     } }