Zip

Generates array tuples from input arrays.

Installation

$ npm install compute-zip

For use in the browser, use browserify.

Usage

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

zip( arr1, arr2,...[, opts] )

Returns an array of arrays, where the ith element (tuple) in the returned array contains the ith elements of the input arrays.

var zipped = zip( [1,2], ['a','b'] );
// returns [ [1,'a'], [2,'b'] ]

By default, the returned array length is the length of the shortest input array.

var zipped = zip( [1,2,3], ['a','b'] );
// returns [ [1,'a'], [2,'b'] ]

The function accepts an options object with optional properties:

• trunc: boolean specifying whether the returned array should truncate arrays longer than the shortest array. Default: true.
• fill: fill value used for unequal length arrays. Default: null.
• arrays: boolean specifying whether, when provided a single input array, the function should interpret the argument as a list of arrays to be zipped (i.e., behavior similar to zip.apply(null, arr)). Default: false.

To turn off truncation,

var opts = {
	'trunc': false
};

var zipped = zip( [1,2,3], ['a','b'], opts );
// returns [ [1,'a'], [2,'b'], [3,null] ]

A fill value is included in each tuple for each array which does not have an element at the ith index. By default, the fill value is null. To specify a different fill value, set the fill option.

var opts = {
	'trunc': false,
	'fill': ''
};

var zipped = zip( [1,2,3], ['a','b'], opts );
// returns [ [1,'a'], [2,'b'], [3,''] ]

If the function should interpret a single input array as an array of arrays to be zipped,

var arr = [[1,2], ['a','b']],
	zipped;

// Default behavior:
zipped = zip( arr );
// returns [ [[1,2]], [['a','b']] ]

// Array of arrays:
zipped = zip( arr, { 'arrays': true } );
// returns [ [1,'a'], [2,'b'] ]

Examples

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

// Simulate some data...
var x = new Array( 100 ),
	len = x.length,
	y1 = new Array( len ),
	y2 = new Array( len ),
	y3 = new Array( len );

for ( var i = 0; i < len; i++ ) {
	x[ i ] = Date.now();
	y1[ i ] = Math.random() * 100;
	y2[ i ] = Math.random() * 100;
	y3[ i ] = Math.random();
}

var zipped = zip( x, y1, y2, y3 );

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

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

$ node ./examples/index.js

Notes

This function is inspired by Python's zip function.

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

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License

MIT license.

Copyright

Copyright © 2014-2015. Athan Reines.