Moving Product

Computes a moving product over an array.

Installation

$ npm install compute-mprod

For use in the browser, use browserify.

Usage

var mprod = require( 'compute-mprod' );

mprod( arr, window[, accessor] )

Slides a window over an array to compute a moving product. For primitive arrays,

var data = [ 1, 2, 3, 4, 5 ];

var arr = mprod( data, 2 );
// returns [ 2, 6, 12, 20 ]

For object arrays, provide an accessor function for accessing array values

var data = [
	{'x':1},
	{'x':2},
	{'x':3},
	{'x':4},
	{'x':5}
];

function getValue( d ) {
	return d.x;
}

var arr = mprod( data, 2, getValue );
// returns [ 2, 6, 12, 20 ]

Note: the returned array has length L - W + 1, where L is the length of the input array and W is the window size.

Examples

var mprod = require( 'compute-mprod' );

// Simulate some data...
var data = new Array( 100 );
for ( var i = 0; i < data.length; i++ ) {
	data[ i ] = Math.round( Math.random()*10 ) + 1;
}
// Compute the moving product:
var arr = mprod( data, 7 );

console.log( arr.join( '\n' ) );

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. Philipp Burckhardt.