Chunkify

Segments an array into chunks.

Installation

$ npm install compute-chunkify

For use in the browser, use browserify.

Usage

To use the module,

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

chunkify( arr, n[, opts] )

Segments an array into chunks of length n.

var data = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];

var out = chunkify( data, 3 );
/* returns
	[
		[1,2,3],
		[4,5,6],
		[7,8,9],
		[10,null,null]
	]
*/

The function is configurable and has the following options...

start

Integer specifying the index from which to begin chunking. Default: 0.

var opts = {
	'start': 2
};

var out = chunkify( data, 3, opts );
/* returns
	[
		[2,3,4],
		[5,6,7],
		[8,9,10]
	]
*/

truncate

Boolean specifying whether the last chunk must contain only array values and no padded values. Default: false.

var opts = {
	'truncate': true
};

var out = chunkify( data, 3, opts );
/* returns
	[
		[1,2,3],
		[4,5,6],
		[7,8,9]
	]
*/

padding

By default, if the array length is not evenly divisible by n, the last chunk is padded with null values. Default: true.

To turn off padding, set this option to false.

var opts = {
	'padding': false
};

var out = chunkify( data, 3, opts );
/* returns
	[
		[1,2,3],
		[4,5,6],
		[7,8,9],
		[10]
	]
*/

padding_value

The default padding value is null. Set this option to pad with a value other than null.

var opts = {
	'padding_value': 0
};

var out = chunkify( data, 3, opts );
/* returns
	[
		[1,2,3],
		[4,5,6],
		[7,8,9],
		[10,0,0]
	]
*/

delay

By default, an array is chunked beginning with the first array element. Default: 0.

Set this option to pad the first chunk, where 0 < delay < n.

var opts = {
	'delay': 2
};

var out = chunkify( data, 3, opts );
/* returns 
	[
		[null,null,1],
		[2,3,4],
		[5,6,7],
		[8,9,10]
	]
*/

overlap

By default, the array is segmented into adjacent chunks (no overlap and no underlap). Default: 0.

To create overlapping chunks, set the overlap option such that 0 < overlap < n,

var opts = {
	'overlap': 2
};

var out = chunkify( data, 3, opts );
/* returns 
	[
		[1,2,3],
		[2,3,4],
		[3,4,5],
		[4,5,6],
		[5,6,7],
		[6,7,8],
		[7,8,9],
		[8,9,10],
		[9,10,null]
	]
*/

To create non-adjacent chunks (underlap), set the overlap such that overlap < 0 , where |overlap| corresponds to the number of elements to skip between new chunks.

var opts = {
	'overlap': -4
};

var out = chunkify( data, 3, opts );
/* returns 
	[
		[1,2,3],
		[8,9,10]
	]
*/

Examples

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

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.