flow-skewness

Reduce stream factory to calculate the sample skewness of streamed data values.

Installation

$ npm install flow-skewness

For use in the browser, use browserify.

Usage

To create a stream factory,

var flowFactory = require( 'flow-skewness' );

// Create a new factory:
var flowStream = flowFactory();

The factory has the following methods...

flowStream.stream()

Creates a new stream for computing the sample skewness. To create a new stream,

var stream = flowStream.stream();

Examples

var eventStream = require( 'event-stream' ),
	flowFactory = require( 'flow-skewness' );

// Create some data...
var data = new Array( 1000 );
for ( var i = 0; i < data.length; i++ ) {
	data[ i ] = Math.random();
}

// Create a readable stream:
var readStream = eventStream.readArray( data );

// Create a new stream:
var stream = flowFactory().stream();

// Pipe the data:
readStream
	.pipe( stream )
	.pipe( eventStream.map( function( d, clbk ){
		clbk( null, d.toString()+'\n' );
	}))
	.pipe( process.stdout );

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

$ node ./examples/index.js

Notes

The formula for computing the sample skewness comes from

Jones and Gill (1998). Comparing measures of sample skewness and kurtosis. The Statistician. DOI: 10.1111/1467-9884.00122

The test data comes from Measures of Shape: Skewness and Kurtosis by Stan Brown.

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,

$ open reports/coverage/lcov-report/index.html

License

MIT license.

Copyright

Copyright © 2014. Athan Reines.