Equal

Computes an element-wise comparison (equality) of an array.

Installation

$ npm install compute-eq

For use in the browser, use browserify.

Usage

To use the module,

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

eq( arr, x[, opts] )

Computes an element-wise comparison (equality) for each input array element. x may either be an array of equal length or a single value (of any type).

The function returns an array with length equal to that of the input array. Each output array element is either 0 or 1. A value of 1 means that an element is equal to a compared value and 0 means that an element is not equal to a compared value.

var arr = [ 5, 3, 8, 3, 2 ],
	out;

// Single comparison value:
out = eq( arr, 3 );
// returns [ 0, 1, 0, 1, 0 ]

// Array of comparison values:
out = eq( arr, [ 5, 2, 8, 7, 3 ] );
// returns [ 1, 0, 1, 0, 0 ]

By default, the function enforces strict equality. To turn off type equality, set the strict options flag to false.

var arr = [ 1, 0, 3, null, undefined ],
	compare = [ true, false, 2, 0, 1 ],
	out;

out = eq( arr, compare );
// returns [ 0, 0, 0, 0, 0 ];

out = eq( arr, compare, {'strict': false} );
// returns [ 1, 1, 0, 0, 0 ] // 0 != null

By default, if provided a comparison array which has a length equal to the input array length, the function assumes an element-by-element comparison. To turn off element-by-element comparison for equal length arrays, set the array options flag to true.

var el = [ 1, 2 ],
	arr = [ el, null ],
	out;

out = eq( arr, el );
// returns [ 0, 0 ];

out = eq( arr, el, {'array': true} );
// returns [ 1, 0 ];

Notes

• Currently, this function only computes shallow equality and does not compute deep equality when comparing arrays or objects.

Examples

var eq = require( 'compute-eq' ),
	sum = require( 'compute-sum' );

// Simulate some data...
var data = new Array( 100 );

for ( var i = 0; i < data.length; i++ ) {
	data[ i ] = Math.round( Math.random()*20 );
}

var out = eq( data, 10 );

// Count the number of values equal to 10...
var count = sum( out );

console.log( 'Total: %d', count );

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 © 2014. Athan Reines.