On Wednesday, 20 July 2022 at 09:18:29 UTC, anonymouse wrote:
As for task 3, while I understand the concept of transposing a
matrix, I'm not sure how to even begin.
By not knowing how to begin, I mean that I don't know how to
generalize the algorithm so that it applies to an array of
arbitrary dimension/shape. If I already know the dimensions, I
can hardcode that information and get it to work just fine. In
the example below, since I know that ```a``` has a shape of [3,
5, 7], I use that information to transpose the array:
```d
import std.traits;
auto transpose(A)(A a) if (isArray!A)
{
auto tmp = new FlatElementType!A[3][5][7]; // [1]
foreach(n0, i; a)
foreach(n1, j; i)
foreach(n2, k; j)
tmp[n2][n1][n0] = k;
return tmp;
}
void main()
{
auto a = [
[
[111,112,113,114,115,116,117],
[121,122,123,124,125,126,127],
[131,132,133,134,135,136,137],
[141,142,143,144,145,136,147],
[151,152,153,154,155,156,137]
],
[
[211,212,213,214,215,216,217],
[221,222,223,224,225,226,227],
[231,232,233,234,235,236,237],
[241,242,243,244,245,236,247],
[251,252,253,254,255,256,237]
],
[
[311,312,313,314,315,316,317],
[321,322,323,324,325,326,327],
[331,332,333,334,335,336,337],
[341,342,343,344,345,336,347],
[351,352,353,354,355,356,337]
]
];
a.transpose.writeln;
}
```
Output reformatted for visual presentation:
```
[
[
[111, 211, 311],
[121, 221, 321],
[131, 231, 331],
[141, 241, 341],
[151, 251, 351]
],
[
[112, 212, 312],
[122, 222, 322],
[132, 232, 332],
[142, 242, 342],
[152, 252, 352]
],
[
[113, 213, 313],
[123, 223, 323],
[133, 233, 333],
[143, 243, 343],
[153, 253, 353]
],
[
[114, 214, 314],
[124, 224, 324],
[134, 234, 334],
[144, 244, 344],
[154, 254, 354]
],
[
[115, 215, 315],
[125, 225, 325],
[135, 235, 335],
[145, 245, 345],
[155, 255, 355]
],
[
[116, 216, 316],
[126, 226, 326],
[136, 236, 336],
[136, 236, 336],
[156, 256, 356]
],
[
[117, 217, 317],
[127, 227, 327],
[137, 237, 337],
[147, 247, 347],
[137, 237, 337]
]
]
```
As the example demonstrates, by knowing beforehand that it is a
3D array of shape [3, 5, 7] , I can hardcode that information
into the temp array and use the correct amount of nested loops to
unwind and reassigned the values. I would like to accomplish this
without knowing the shape before hand.
Any pointers would be appreciated.
Thanks,
--anonymouse
[1] Contributed by
[ag0aep6g](https://forum.dlang.org/post/tb9pl1$gc1$1...@digitalmars.com)
