# compute-eq

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

## Stats

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compute-eq
1.0.09 years ago9 years ago

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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``