On Tuesday, 9 October 2018 at 10:52:47 UTC, Chris Katko wrote:
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))
So according to this:
https://dlang.org/library/std/range/transposed.html
It's trying to take my [0] as an argument for the
TransverseOptions variable? But even if I wrap it in parenthesis,
it still takes it! (See the last line of code.)
auto taco = (data.transposed);
run_rle3(taco); //same error, but <-------- HERE?
