https://github.com/phughesmcr/grid-neighbors-1d

Get the 8 directional neighbors of a cell in a 1d array
https://github.com/phughesmcr/grid-neighbors-1d

1d 2d array game-of-life grid javascript neighbors neighbours node

Last synced: 12 days ago
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Get the 8 directional neighbors of a cell in a 1d array

• Host: GitHub
• URL: https://github.com/phughesmcr/grid-neighbors-1d
• Owner: phughesmcr
• License: mit
• Created: 2019-04-02T15:21:00.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2023-11-01T07:11:11.000Z (about 1 year ago)
• Last Synced: 2024-05-01T19:29:06.411Z (8 months ago)
• Topics: 1d, 2d, array, game-of-life, grid, javascript, neighbors, neighbours, node
• Language: TypeScript
• Size: 201 KB
• Stars: 3
• Watchers: 1
• Forks: 1
• Open Issues: 5
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# grid-neighbors-1d

Get the 8 closest neighbors of a grid with edge wrapping from a 1d array

## Why?

![grid-neighbors](https://raw.githubusercontent.com/phugh/grid-neighbors-1d/master/grid-neighbors.png)

## Usage

Get the neighbors of cell 12 in a 5x5 grid:

```javascript

import { getNeighbors } from "grid-neighbors-1d";

const neighbors = getNeighbors(12, 5, 5);

console.log(neighbors); // [7, 8, 13, 18, 17, 16, 11, 6] - clockwise from north

```

`getNeighbors` returns an array of indexes of the cell immediately to the north of the chosen cell, then clockwise around the remaining cells:

* neighbors[0] = north neighbor

* neighbors[1] = north-east neighbor

* neighbors[2] = east neighbor

* neighbors[3] = south-east neighbor

* neighbors[4] = south neighbor

* neighbors[5] = south-west neighbor

* neighbors[6] = west neighbor

* neighbors[7] = north-west neighbor

This means you can use destructuring if your environment supports it:

```javascript

const [north, northEast, east, southEast, south, southWest, west, northWest] = getNeighbors(4, 10, 6);

```

A `Direction` object is also available for convenience:

```javascript

import { Direction } from "grid-neighbors-1d";

const neighbors = getNeighbors(12, 5, 5);

console.log(neighbors[Direction.NORTH]); // 7

```

If memory usage is not a concern and you are likely to call `getNeighbors` many times, you may want to precalculate the neighbors for a given grid size:

```javascript

import { generateNeighborLookup } from "grid-neighbors-1d";

const getNeighbors = generateNeighborLookup(5, 5);

const neighbors = getNeighbors(12);

console.log(neighbors); // [7, 8, 13, 18, 17, 16, 11, 6]

```

For your convenience, TypeScript type declarations (index.d.ts), a declaration map (index.d.ts.map), and a sourcemap (index.js.map) are included.

## License

© 2019-23 [P. Hughes](https://www.phugh.es). All rights reserved.

Shared under the [MIT](https://choosealicense.com/licenses/mit/) license.