Hi.
Is there a Built-in function (no code, only a built-in function)
that transform a linear array to a Matrix?

For example:

From

[10,20,30,40,50,60,70,80,90,100,110,120];


To

[
[10,20,30],
[40,50,60],
[70,80,90],
[100,110,120]
];

Thank You very much
Cheers.
Giovanni

On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
> Hi.
> Is there a Built-in function (no code, only a built-in function)
> that transform a linear array to a Matrix?
>
> For example:
>
> From
>
> [10,20,30,40,50,60,70,80,90,100,110,120];
>
>
> To
>
> [
> [10,20,30],
> [40,50,60],
> [70,80,90],
> [100,110,120]
> ];
>
> Thank You very much
> Cheers.
> Giovanni

If you're really sure about the array and matrix dimensions/types.
You can use a cast:

    int[] a = [10,20,30,40,50,60,70,80,90,100,110,120];

    int[3][] m1 = cast(int[3][]) a;
    writeln(m1);

A better way is using the function chunks;

    import std.range;

    auto m2 = a.chunks(3);
    writeln(m2);

On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
> Is there a Built-in function (no code, only a built-in function)
> that transform a linear array to a Matrix?

You can combine slide [1] and array [2]:

import std;

void main()
{
    auto input = [10,20,30,40,50,60,70,80,90,100,110,120];
    auto output = input.slide(3, 3).array;

    writeln(input);
    writeln();
    writeln(output);
}

Note that output is a view of input and not a copy.

[1] https://dlang.org/phobos/std_range.html#.slide
[2] https://dlang.org/phobos/std_array.html#.array

On Saturday, 4 April 2020 at 10:52:00 UTC, Boris Carvajal wrote:
> On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
>> Hi.
>> Is there a Built-in function (no code, only a built-in function)
>> that transform a linear array to a Matrix?
>>
>> For example:
>>
>> From
>>
>> [10,20,30,40,50,60,70,80,90,100,110,120];
>>
>>
>> To
>>
>> [
>> [10,20,30],
>> [40,50,60],
>> [70,80,90],
>> [100,110,120]
>> ];
>>
>> Thank You very much
>> Cheers.
>> Giovanni
>
> If you're really sure about the array and matrix dimensions/types.
> You can use a cast:
>
>     int[] a = [10,20,30,40,50,60,70,80,90,100,110,120];
>
>     int[3][] m1 = cast(int[3][]) a;
>     writeln(m1);
>
> A better way is using the function chunks;
>
>     import std.range;
>
>     auto m2 = a.chunks(3);
>     writeln(m2);



Ok. Thank you for your help
Giovanni

On Saturday, 4 April 2020 at 10:52:30 UTC, MoonlightSentinel wrote:
> On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
>> Is there a Built-in function (no code, only a built-in function)
>> that transform a linear array to a Matrix?
>
> You can combine slide [1] and array [2]:
>
> import std;
>
> void main()
> {
>     auto input = [10,20,30,40,50,60,70,80,90,100,110,120];
>     auto output = input.slide(3, 3).array;
>
>     writeln(input);
>     writeln();
>     writeln(output);
> }
>
> Note that output is a view of input and not a copy.
>
> [1] https://dlang.org/phobos/std_range.html#.slide
> [2] https://dlang.org/phobos/std_array.html#.array



Thank you very much.
Giovanni

On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
> Hi.
> Is there a Built-in function (no code, only a built-in function)
> that transform a linear array to a Matrix?
>
> For example:
>
> From
>
> [10,20,30,40,50,60,70,80,90,100,110,120];
>
>
> To
>
> [
> [10,20,30],
> [40,50,60],
> [70,80,90],
> [100,110,120]
> ];
>
> Thank You very much
> Cheers.
> Giovanni

You may want to look into a mir-algorithm package that supports rectangular multidimensional arrays like NumPy.

/+dub.sdl:
dependency "mir-algorithm" version="~>3.7.27"
+/

// http://mir-algorithm.libmir.org/mir_ndslice.html

import mir.ndslice;

void main()
{
    //
    auto intArray = [10,20,30,40,50,60,70,80,90,100,110,120];
    auto intMatrix = intArray.sliced(4, 3);

    static assert(is(typeof(intMatrix) == Slice!(int*, 2)));

    // lazy matrix
    auto lazyMatrix = iota!int([4, 3]/*shape*/, 10/*start*/, 10/*stride*/);
    assert(intMatrix == lazyMatrix);
    //or
    foreach(i; 0 .. intMatrix.length)
    	foreach(j; 0 .. intMatrix.length!1)
        	assert(intMatrix[i, j] == lazyMatrix[i, j]);
        	
}

On Saturday, 4 April 2020 at 14:00:01 UTC, 9il wrote:
> On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
>> [...]
>
> You may want to look into a mir-algorithm package that supports rectangular multidimensional arrays like NumPy.
>
> [...]




Very good.
Thank you!!!!
G

On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
> Hi.
> Is there a Built-in function (no code, only a built-in function)
> that transform a linear array to a Matrix?
>
> For example:
>
> From
>
> [10,20,30,40,50,60,70,80,90,100,110,120];
>
>
> To
>
> [
> [10,20,30],
> [40,50,60],
> [70,80,90],
> [100,110,120]
> ];
>
> Thank You very much
> Cheers.
> Giovanni

Why not use "chunks" from std.range?

import std.range: chunks;

void main() {
    int[] arr = [10,20,30,40,50,60,70,80,90,100,110,120];
    auto matrix1 = arr.chunks(3).chunks(4); // no allocation
    int[][][] matrix2 = arr.chunks(3).array.chunks(4).array;
}

But, keep in mind using array of arrays is not efficient.
For multidimensional arrays use Mir Slices.
If you need more information on how to create matrices, see this article: https://tastyminerals.github.io/tasty-blog/random/2020/03/22/multidimensional_arrays_in_d.html

On Sunday, 5 April 2020 at 18:58:17 UTC, p.shkadzko wrote:
> On Saturday, 4 April 2020 at 09:25:14 UTC, Giovanni Di Maria wrote:
>> [...]
>
> Why not use "chunks" from std.range?
>
> import std.range: chunks;
>
> void main() {
>     int[] arr = [10,20,30,40,50,60,70,80,90,100,110,120];
>     auto matrix1 = arr.chunks(3).chunks(4); // no allocation
>     int[][][] matrix2 = arr.chunks(3).array.chunks(4).array;
> }
>
> But, keep in mind using array of arrays is not efficient.
> For multidimensional arrays use Mir Slices.
> If you need more information on how to create matrices, see this article: https://tastyminerals.github.io/tasty-blog/random/2020/03/22/multidimensional_arrays_in_d.html

it should be just one call to chunks --> arr.chunks(3), otherwise you'll get two nested arrays while you need only one. Sorry for confusion.