What's the best way to extract a one-dimensional array from a rectangular array in C#?

Question

Say I have a rectangular string array - not a jagged array

string[,] strings = new string[8, 3];

What's the best way to extract a one-dimensional array from this (either a single row or a single column)? I can do this with a for loop, of course, but I'm hoping .NET has a more elegant way built in.

Bonus points for converting the extracted string array to an object array.

Answer 1

You can cast a string array to an object array trivially - going the other way doesn't work. The actual extraction has to use a for loop though, as far as I can see: Array.Copy requires the source and target ranks to be the same, and Buffer.BlockCopy only works for value type arrays. It does seem odd though...

You can use LINQ to extra a row or column in a single statement, although it will be inefficient (as it'll build up a list internally, then have to convert it to an array - if you do it yourself you can preallocate the array to the right size and copy directly).

Copying a row (rowNum is the row to be copied):

object[] row = Enumerable.Range(0, rowLength)
                         .Select(colNum => (object) stringArray[rowNum, colNum])
                         .ToArray();

Copying a column (colNum is the column to be copied):

object[] column = Enumerable.Range(0, columnLength)
                            .Select(rowNum => (object) stringArray[rowNum, colNum])
                            .ToArray();

I'm not sure that this is really any better/simpler than a foreach loop though - particularly if you write an ExtractRow method and an ExtractColumn method and reuse them.