Given an array of arbitrary dimensions, I would like to
accomplish three things:
1) verify that it is rectangular (e.g. all elements have
the same length, all sub-elements have the same length, etc.)
2) flatten and return the flattened copy
3) transpose and return the transposed copy
Here is my naive attempt to accomplish the first task:
````d
auto isRectangular(A)(A a) if (isArray!A)
{
bool result;
size_t length = a[0].length;
foreach (e; a) {
result = e.length == length;
}
return result;
}
````
This only works if ````a```` is a 2D array, how do I extend this
to support arrays with larger dimensions (3D, 4D, 5D, etc.)?
For task 3, I can visit each element of the array, but I have no
idea how to compose the flattened (1D) version:
````d
import std.range.primitives: ElementType;
auto flatten(A)(A a) if (isArray!A)
{
//ElementType!(A)[] result; //[1]
foreach (i; a) {
static if (isArray!(typeof(i)))
flatten(i);
else {
writeln(i);
// result ~= i; //[2]
}
}
//return result; // [3]
}
````
The thought I had was to get the BaseType of the array (int,
double, etc.) and use it to create a dynamic array [1]. I could
then concatenate each element [2], and return the result once
completed [3]. This approach has two major problems and probably
many other's I'm not yet experienced enough to see. The first is
that there's no way to get the BaseType of an array. ElementType
in the example assumes that array is 2D, therefore anything else
passed in will result in a multi-dimensional array being created
to which individual elements cannot be concatenated. The second
issue is that each call to flatten will have it's own result
which will be discarded when the function exits, so the final
result will be an empty array.
As for task 3, while I understand the concept of transposing a
matrix, I'm not sure how to even begin.
These tasks are all self assigned and not associated with any
high school or college course. Just trying get a better
understanding of how arrays and matrices/tensors work while
reading up on linear algebra. This is purely self study and I
would really appreciate some assistance.
Thanks,
---anonymouse
