Does anyone know if multik has something like np.roll() for d2Array?

Unfortunately, there is no such method in multik

Are you aware of any alternatives for kotlin?

For any dimension?

I'm working with d2Array

roll

without specifying an axis, it’s just a shift. You can use `Collections.rotate`:

fun D2Array<Int>.roll(n: Int): D2Array<Int> {
    val data = this.toList().also { Collections.rotate(it, n) }
    return D2Array(MemoryViewIntArray(data.toIntArray()), shape = this.shape.clone(), dim = this.dim)
}

or use

sliceArray

fun D2Array<Int>.roll(n: Int): D2Array<Int> {
    val newData = this.data.getIntArray().let { it.sliceArray(size - n until size) + it.sliceArray(0 until size - n) }
    return D2Array(MemoryViewIntArray(newData), shape = this.shape.clone(), dim = this.dim)
}

I do need an axis though 😄 Here's what I'm trying to do

img = np.roll(img, dy, axis=0)
 img = np.roll(img, dx, axis=1)

with axes are more complicated There are no functions from kotlin for this, here need to work with

strides

Might sound a bit dense, but what do axes mean in 2darray context here?

Same as in numpy, axis(1) by columns or axis(0) by rows

🤦‍♂️ so basically dimensions. Thought so...

In KMathe it is planed to do that with virtual buffers. But manipulating strides is a more performant solution. I wonder if roll have a lot of uses outside numpy paradigm (I meant when you can't work with elements in a cycle). @Big Chungus could you explain the problem you are solving.

Not sure I can. I'm basically getting my feet wet with OpenCV and image transformations. Here's a PY algorithm I'm trying to reproduce to shift image https://stackoverflow.com/a/53140617

Yeah, a lot of holes in it and too many experiments so far. For simple 2d manipulation Multik could be better so far.