Welcome to the documentation of ndarray-js

Features

The library implements a large subset of numpy operations

// Feature 1: A parsing system that can interpret numpy code as ndarray-js instructions
x = np`np.exp(0.5 * np.linspace(0, 1, 100).reshape(5, 4, 5)).mean(axis=0)`
y = np`(${x} * ${x}) / 2`

// Equivalent code:
x = np.exp(0.5 * np.linspace(0, 1, 100).reshape(5, 4, 5)).mean({axis:0})
y = np.divide(np.multiply(x * x), 2)


// Feature 2. Handling of args and kwargs following numpy order
x = np.geomspace(1, 10, 100).reshape([10,10])
x.mean({axis: -1, keepdims: true})
x.mean(-1, true)
x.mean(-1, {keepdims: true})
np.mean(x, {axis: -1})


// Feature 3. All types of indexing: (number, start:end:step, ':', '...', list of indices, NDArray boolean mask, NDArray boolean mask, NDArray indices)
y = x.index(2, ':', mask, '...', indices, '-1:-1:-2', -1);
y = np`${x}[2, :, ${mask}, ..., ${indices}, -1:-1:-2, -1]`;

// Feature 4. Broadcasting:
mu = np.array([1.5, 0]);
x = np.random.randn([100, 2]).add(x);
norm = x.pow(2).sum({axis: -1}).pow(0.5);
x.divide_assign(norm.index(':', 'None'));
for(let point2d of x){
  console.log(point2d.tolist(), point2d.norm(), point2d.max());
  if(np.all(point2d.equal(x.index(5)))) break;
}
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API Index

• Global namespace: np
• NDArray class: np.NDArray.

Browser usage

In html:

<script src="https://cdn.jsdelivr.net/npm/ndarray-js@latest/dist/index.js"></script>
<script>
a = np.arange(18).reshape(3, 2, 3);
console.log(a.tolist());
</script>
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Or press F12 and play with the browser console directly.

Node usage

Installation:

npm install ndarray-js
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Use in nodejs with require:

const { np } = require('ndarray-js');
a = np.arange(18).reshape(3, 2, 3);
console.log(a.tolist());
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Use in nodejs with typescript (run with ts-node or compile with tsc):

import { np } from 'ndarray-js';
const a = np.arange(18).reshape(3, 2, 3);
console.log(a.tolist());
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Use in Jupyter notebooks:

You need to install the ipykernel (the setup is a bit more complex).

Example notebook: https://github.com/caph1993/numpy-js/blob/main/notebooks/normal-scatter.ipynb