Midmean

Computes the interquartile mean (midmean) of a numeric array.

Installation

$ npm install compute-midmean

For use in the browser, use browserify.

Usage

To use the module,

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

midmean( arr[, sorted] )

Computes the midmean of a numeric array.

var unsorted = [ 5, 6, 7, 2, 1, 8, 4, 3 ];

var mean = midmean( unsorted );
// returns 4.5

If the input array is already sorted in ascending order, set the optional second argument to true.

var sorted = [ 1, 2, 3, 4, 5, 6, 7, 8 ];

var mean = midmean( sorted, true );
// returns 4.5

Examples

var data = new Array( 100 );

for ( var i = 0; i < data.length; i++ ) {
    data[ i ] = Math.round( Math.random()*100 );
}

console.log( midmean( data ) );

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

$ node ./examples/index.js

Notes

If provided an unsorted input array, the function is O( N log(N) + m ), where N is the input array length and m is the number of values located between the first and third quartiles. If the input array is already sorted in ascending order, the function is O(m).

The midmean includes the values located between but not including the first and third quartiles. In the following examples, the values included in the midmean are in bold.

• [1,2,3,4,5,6,7,8] -> midmean: 4.5
• [1,2,3,4,5,6,7] -> midmean: 4

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. Rebekah Smith.