compute-chebyshev-distance

Chebyshev Distance
===
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> Computes the Chebyshev distance between two arrays.

The Chebyshev distance is a metric defined on a vector space where the distance between two vectors is the greatest difference along any coordinate dimension.

Installation

`` bash
$ npm install compute-chebyshev-distance
`

For use in the browser, use browserify.

Usage

` javascript
var chebyshev = require( 'compute-chebyshev-distance' );
`

#### chebyshev( x, y[, accessor] )

Computes the Chebyshev distance between two arrays.

` javascript
var x = [ 2, 4, 5, 3, 8, 2 ],
y = [ 3, 1, 5, -3, 7, 2 ];

var d = chebyshev( x, y );
// returns 6
`

For object arrays, provide an accessor function for accessing numeric values.

` javascript
var x, y, d;

x = [
[1,2],
[2,4],
[3,5],
[4,3],
[5,8],
[6,2]
];

y = [
{'y':3},
{'y':1},
{'y':5},
{'y':-3},
{'y':7},
{'y':2}
];

function getValue( d, i, j ) {
if ( j === 0 ) {
return d[ 1 ];
}
return d.y;
}

var d = chebyshev( x, y, getValue );
// returns 6
`

The accessor function is provided three arguments:

- __d__: current datum.
- __i__: current datum index.
- __j__: array index; e.g., array x has index 0 and array y has index 1.


If provided empty arrays, the function returns null.

Examples

` javascript
var chebyshev = require( 'compute-chebyshev-distance' );

var x = new Array( 100 ),
y = new Array( 100 );

for ( var i = 0; i < x.length; i++ ) {
x[ i ] = Math.round( Math.random()*100 );
y[ i ] = Math.round( Math.random()*100 );
}

console.log( chebyshev( x, y ) );
`

To run the example code from the top-level application directory,

` bash
$ node ./examples/index.js
`

Tests

$3

Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:

` bash
$ make test
`

All new feature development should have corresponding unit tests to validate correct functionality.

$3

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

` bash
$ make test-cov
`

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

` bash
$ make view-cov
``

---

License

MIT license.

Copyright

Copyright © 2015. Philipp Burckhardt.

[npm-image]: http://img.shields.io/npm/v/compute-chebyshev-distance.svg
[npm-url]: https://npmjs.org/package/compute-chebyshev-distance

[travis-image]: http://img.shields.io/travis/compute-io/chebyshev-distance/master.svg
[travis-url]: https://travis-ci.org/compute-io/chebyshev-distance

[coveralls-image]: https://img.shields.io/coveralls/compute-io/chebyshev-distance/master.svg
[coveralls-url]: https://coveralls.io/r/compute-io/chebyshev-distance?branch=master

[dependencies-image]: http://img.shields.io/david/compute-io/chebyshev-distance.svg
[dependencies-url]: https://david-dm.org/compute-io/chebyshev-distance

[dev-dependencies-image]: http://img.shields.io/david/dev/compute-io/chebyshev-distance.svg
[dev-dependencies-url]: https://david-dm.org/dev/compute-io/chebyshev-distance

[github-issues-image]: http://img.shields.io/github/issues/compute-io/chebyshev-distance.svg
[github-issues-url]: https://github.com/compute-io/chebyshev-distance/issues