How to use LINQ on a multidimensional array to 'unwind' the array?

Question

Consider the following array:

int[,] numbers = new int[3, 2] { { 2, 1 }, { 3, 4 }, { 6, 5 } };

I would like to use LINQ to construct an IEnumerable with numbers 2, 1, 3, 4, 6, 5.

What would be the best way to do so?

possible duplicate of [Convert 2 dimensional array](http://stackoverflow.com/questions/641499/convert-2-dimensional-array) — Ben Robinson, Dec 11 '12 at 15:20
There is a linq query in the duplicate, but i would go with a foreach as the linq query is quite opaque and the foreach is clear what you are doing. — Ben Robinson, Dec 11 '12 at 15:21
@BenRobinson, I need to use LINQ, the other problem does not use LINQ. — Kees C. Bakker, Dec 11 '12 at 15:22
'var flatNumbers = numbers.Cast();' copied and modified from the linked post. All LINQ — Ben Robinson, Dec 11 '12 at 15:24
@KeesC.Bakker I rolled back your last edits, because that was radical change of your initial question — Sergey Berezovskiy, Dec 11 '12 at 15:35
@lazyberezovsky, just added a second post with the LINQ question. — Kees C. Bakker, Dec 11 '12 at 15:40

score 28 · Answer 1 · answered Dec 11 '12 at 15:22

28

Perhaps simply:

var all = numbers.Cast<int>();

Demo

answered Dec 11 '12 at 15:22

Tim Schmelter

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1

+1 from me - `Cast` is a has a little less overhead then `OfType` in this case – Sergey Berezovskiy Dec 11 '12 at 15:39
2

Upvoted. But in either way we get _boxing_ and _unboxing_ because this goes through the non-generic `IEnumerable` interface which yields `object` boxes which are the unboxed by `Cast`. – Jeppe Stig Nielsen Dec 12 '12 at 09:29

score 7 · Accepted Answer · edited Dec 07 '14 at 19:11

How about:

Enumerable
    .Range(0,numbers.GetUpperBound(0)+1)
    .SelectMany(x => Enumerable.Range(0,numbers.GetUpperBound(1)+1)
    .Select (y =>numbers[x,y] ));

or to neaten up.

var xLimit=Enumerable.Range(0,numbers.GetUpperBound(0)+1);
var yLimit=Enumerable.Range(0,numbers.GetUpperBound(1)+1);
var result = xLimit.SelectMany(x=> yLimit.Select(y => numbers[x,y]));

EDIT Revised Question....

var result = array.SelectMany(x => x.C);

Sergey Berezovskiy · Answer 3 · 2012-12-11T15:38:03.927

6

Use simple foreach to get your numbers from 2d array:

int[,] numbers = new int[3, 2] { { 2, 1 }, { 3, 4 }, { 6, 5 } };
foreach(int x in numbers)
{
   // 2, 1, 3, 4, 6, 5.
}

LINQ (it's an big overhead to use Linq for your initial task, because instead of simple iterating array, CastIterator (Tim's answer) of OfTypeIterator will be created)

IEnumerable<int> query = numbers.OfType<int>();

edited Dec 11 '12 at 15:38

answered Dec 11 '12 at 15:18

Sergey Berezovskiy

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I need to use LINQ. My problem is a tat more complex... but I need to use LINQ. Each object in the array has a property that has an array that I'll need to mash into a single list. – Kees C. Bakker Dec 11 '12 at 15:21
1

Please post your whole problem as you will get different answers – Ben Robinson Dec 11 '12 at 15:21
2

It may be homework, but it may also be the smallest working example of a mind-bogglingly complex system, which the asker didn't want to bother us with ;-) – Tempestas Ludi Dec 18 '17 at 22:53

How to use LINQ on a multidimensional array to 'unwind' the array?

3 Answers3

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