patgrasso/multiarray

:bullettrain_side: Very fast multidimensional arrays for JS, inspired by ndarray

multiarray 🚄

Very fast multidimensional arrays for javascript.

Purpose

The idea of multiarray is to bring matrix-like datastructures found in libraries like numpy and the GNU Scientific Library to javascript. Trivial implementations of this can be simply achieved by using nested arrays, but this is extremely slow.

multiarray performs just as quickly as ndarray, but is much more flexible and extensible.

var m = new MultiArray([[1, 2], [3, 4]]);

// m
// 2dArray [[1, 2],
//          [3, 4]]

m.get(0, 1)
// 2
m.set(0, 1, 9)
// 2dArray [[1, 9],
//          [3, 4]]

Methods

Methods can be attached to the multiarray prototype like so...

const MultiArray = require('multiarray');

// Get the dimensionality of a matrix
function dimsFactory(props) {
  return function () {
    return props.d;
  }
}

MultiArray.method('dims', dimsFactory);

new MultiArray([[[1, 2],
                 [3, 4]],
                [[5, 6],
                 [7, 8]]]).dims();
// 3

The function supplied to method(name, factory) should be a factory that takes in an object that looks like this:

// props =
{
  d   : < # of dimensions >
  type: < type of the underlying array (Array, Uint32Array, ...)
}

And returns a function that will serve as the method. This allows you to tailor a method to suit matrices of different types and dimensionalities. This is how get() and set() are defined for the multiarray. The actual get() function varies depending on the dimensionality of a matrix in order to improve indexing speed.

Inspiration

This project is heavily inspired by ndarray. While this may seem redundant (why not just fork?), the source code for multiarray is drastically different. In the future, I might try to merge this into ndarray, but for now I'll just continue to build it out here and make it as compliant as possible with ndarray without sacrificing (and perhaps improving) performance.

License

MIT