Cosine Similarity
Computes the cosine similarity between two arrays.
Cosine similarity defines vector similarity in terms of the angle separating two vectors.
Installation
$ npm install compute-cosine-similarity
For use in the browser, use browserify.
Usage
var similarity = require( 'compute-cosine-similarity' );
similarity( x, y[, accessor] )
Computes the cosine similarity between two arrays.
var x = [ 5, 23, 2, 5, 9 ],
y = [ 3, 21, 2, 5, 14 ];
var s = similarity( x, y );
// returns ~0.975
For object arrays, provide an accessor function for accessing numeric values.
var x = [
{'x':2},
{'x':4},
{'x':5}
];
var y = [
[1,3],
[2,1],
[3,5]
];
function getValue( d, i, j ) {
if ( j === 0 ) {
return d.x;
}
return d[ 1 ];
}
var s = similarity( x, y, getValue );
// returns ~0.882
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
var similarity = require( 'compute-cosine-similarity' );
var x = new Array( 100 ),
y = new Array( 100 ),
s;
for ( var i = 0; i < x.length; i++ ) {
x[ i ] = Math.round( Math.random()*100 );
y[ i ] = Math.round( Math.random()*100 );
}
s = similarity( x, y );
console.log( s );
To run the example code from the top-level application directory,
$ node ./examples/index.js
Tests
Unit
Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:
$ make test
All new feature development should have corresponding unit tests to validate correct functionality.
Test Coverage
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:
$ make test-cov
Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,
$ make view-cov
License
MIT license.
Copyright
Copyright © 2015. The Compute.io Authors. All rights reserved.
