How do you iterate "vertically" over a 2-D array?

[Chris Katko]

I have a 2-D array:

int[5][5] data =
	[
		[1, 0, 1, 0, 0],
		[1, 0, 1, 0, 0],
		[1, 0, 1, 1, 1],
		[1, 0, 0, 1, 0],
		[1, 1, 1, 1, 0]
	];


1 - Is there a way to foreach vertically through that? (that is, 
rotated 90 degrees from the usual iteration.)

2 - Is there a way to send that "vertical slice" to a function?

int count_numbers(){/*...*/}

count_numbers(data[0]); //horizontal sum of array[0][0..$-1] 
WORKS.
count_numbers(data[][0]); //vertical sum of array[0..$-1][0] 
HYPOTHETICAL

I'm working on an RLE encoding function and I need both vertical 
and horizontal strips. It just occurred to me that the problem is 
essentially the same, if you can "transpose" the matrix.

Oh geez, did I just realize what I need? some sort of matrix 
transpose function? I found this post;

https://forum.dlang.org/post/na8ikk$2ojo$1@digitalmars.com

The problem is though, even if I use [][], instead of [5][5] (or 
try using his conversion function), I can call transposed... but 
I can't call my function with it!

void run_rle3(int [] a){/*...*/}

	run_rle3(data[0]); //works
	run_rle3(data.transposed[0]); //nope [see error below]
	run_rle3(data[0].transposed); //nope (didn't expect this to)
	run_rle3((data.transposed)[0]); //nope [see error below]

Error: function dmap.run_rle3 (int[] a) is not callable using 
argument types (Transversal!(int[][], cast(TransverseOptions)0))