Rotate array in writefln?

[Simen Kjærås]

On Wednesday, 18 April 2018 at 06:54:29 UTC, Chris Katko wrote:
> I need to rotate an array by 90 degrees, or have writefln 
> figure that out.
>
> I need, say:
>
> 0 4 5 6
> 0 0 0 0
> 0 0 0 0
> 0 0 0 0
>
> But it's outputting:
>
> 0 0 0 0
> 4 0 0 0
> 5 0 0 0
> 6 0 0 0
>
> int [4][4] data;
> file.writeln(format("%(%-(%d %)\n%)", data));

Generally, the solution would be std.range.transposed. However, 
since you're using a int[4][4], that's not a range-of-ranges, and 
transposed don't work out of the box. This helper function should 
help:

T[][] ror(T, size_t N1, size_t N2)(ref T[N1][N2] arr)
{
     T[][] result = new T[][N2];
     foreach (i, e; arr) {
         result[i] = e.dup;
     }
     return result;
}

unittest
{
     import std.stdio;
     import std.range;

     int [4][4] data;
     data[2][3] = 4;
     writefln("%(%-(%d %)\n%)", data);
     writefln("%(%-(%d %)\n%)", data.ror.transposed);
}

--
   Simen