Re: Transposing a static array

[cym13 via Digitalmars-d-learn]

On Saturday, 20 February 2016 at 02:26:56 UTC, maik klein wrote:
On Saturday, 20 February 2016 at 02:22:12 UTC, Ali Çehreli 
wrote:
On 02/19/2016 06:00 PM, maik klein wrote:
How would I transpose
float[3][2]

to

float[2][3]

with http://dlang.org/phobos/std_range.html#.transposed



Because static arrays are not ranges, they must be used as 
slices with the help of []. The following code does the same 
thing in two different ways:

import std.stdio;
import std.range;
import std.algorithm;

void main() {
    float[3][2] arr = [ [1, 2, 3],
                        [4, 5, 6] ];

    // Method A
    {
        float[][] arr2;

        foreach (ref a; arr) {
            arr2 ~= a[];
        }

        writeln(arr2.transposed);
    }

    // Method B
    {
        auto r = arr[].map!((ref a) => a[]).array.transposed;
        writeln(r);
    }
}

Ali

Your "Method B" is how I did it too but how do I convert it 
back to a static array of float[2][3]?

I don't see the point of using transposed which gives a range out 
if you want to put it back into a float[2][3] right away, just do 
a double foreach:

    void main(string[] args) {
        float[3][2] src = [[1, 2, 3], [2, 3, 4]];

        float[2][3] dst;

        foreach (i ; 0..src.length)
            foreach (j ; 0..src[0].length)
                dst[j][i] = src[i][j];

        assert(dst == [[1, 2], [2, 3], [3, 4]]);
    }