Lower Midmean
Computes the lower interquartile mean (lower midmean) of a numeric array.
Installation
$ npm install compute-lmidmean
For use in the browser, use browserify.
Usage
To use the module,
var lmidmean = require( 'compute-lmidmean' );
lmidmean( arr[, sorted] )
Computes the lower midmean for a numeric array
. This is computed by discarding all values above the median and calculating the mean of those values falling between the first and third quartiles.
Note: the input array must contain 6 or more elements.
var unsorted = [ 5, 6, 7, 2, 1, 8, 4, 3 ];
var mean = lmidmean( unsorted );
// returns 2.5
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 = lmidmean( sorted, true );
// returns 2.5
Examples
var data = new Array( 100 );
for ( var i = 0; i < data.length; i++ ) {
data[ i ] = Math.round( Math.random()*100 );
}
console.log( lmidmean( 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 of the lower range. If the input array
is already sorted in ascending order, the function is O(m)
.
The lower midmean includes the values located between but not including the first and third quartiles of the lower range. In the following examples, the values included in the lower midmean are in bold.
-
[1,2,3,4,5,6,7,8] —> lmidmean: 2.5
-
[1,2,3,4,5,6,7,8,9,10,11,12] —> lmidmean: 3.5
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
Copyright
Copyright © 2014. Rebekah Smith.