I'm looking to slice a two dimensional array in C#.
I have double[2,2] prices and want to retrieve the second row of this array. I've tried prices[1,], but I have a feeling it might be something else.
Thanks in advance.
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Strange but it still not possible for C# learn.microsoft.com/en-us/dotnet/csharp/language-reference/… . And works perfectly for F# learn.microsoft.com/en-us/dotnet/fsharp/language-reference/…XperiAndri– XperiAndri2022-04-08 21:29:30 +00:00Commented Apr 8, 2022 at 21:29
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4 Answers
There's no direct "slice" operation, but you can define an extension method like this:
public static IEnumerable<T> SliceRow<T>(this T[,] array, int row)
{
for (var i = 0; i < array.GetLength(0); i++)
{
yield return array[i, row];
}
}
double[,] prices = ...;
double[] secondRow = prices.SliceRow(1).ToArray();
3 Comments
Hamish Grubijan
What does
this do in this T[,] array?
dtb
@Hamish Grubijan: It turns the static method into an extension method.
tsul
Don't you misplace the
row index here as I thought that it should be array[row,column] ?The question is if you have a jagged or a multidimensional array... here's how to retrieve a value from either:
int[,] rectArray = new int[3,3]
{
{0,1,2}
{3,4,5}
{6,7,8}
};
int i = rectArray[2,2]; // i will be 8
int[][] jaggedArray = new int[3][3]
{
{0,1,2}
{3,4,5}
{6,7,8}
};
int i = jaggedArray[2][2]; //i will be 8
EDIT: Added to address the slice part...
To get an int array from one of these arrays you would have to loop and retrieve the values you're after. For example:
public IEnumerable<int> GetIntsFromArray(int[][] theArray) {
for(int i = 0; i<3; i++) {
yield return theArray[2][i]; // would return 6, 7 ,8
}
}
1 Comment
JeffH
OP wrote" "...want to retrieve the second row..." In your example, I think OP wants jaggedArray[2] or an int[3] that contains {6,7,8}
In .NET Core 2.1 and later, you can use MemoryMarshal.CreateSpan<T>(T, Int32) method to create a linear span from a multidimensional array and then Slice() the span to your liking.
double[,] table =
{
{ 12.345, 67.890 },
{ 23.456, 78.901 }
};
var tableSpan = MemoryMarshal.CreateSpan(ref table[0, 0], table.Length);
// tableSpan here is linear: [12.345, 67.890, 23.456, 78.901]
Span<double> slice = tableSpan.Slice(2, 2);
double[] oneDimension = slice.ToArray();
// at this point both slice and oneDimension are: [23.456, 78.901]
