# compute-umidmean

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

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compute-umidmean
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Upper Midmean
!NPM versionnpm-imagenpm-url !Build Statustravis-imagetravis-url !Coverage Statuscoveralls-imagecoveralls-url !Dependenciesdependencies-imagedependencies-url
Computes the upper interquartile mean (upper midmean) of a numeric array.

## Installation

``\$ npm install compute-umidmean``

For use in the browser, use browserify.

## Usage

To use the module,
``var umidmean = require( 'compute-umidmean' );``

#### umidmean( arr, sorted )

Computes the upper midmean of a numeric `array`. This is computed by discarding all values below 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 = umidmean( unsorted );
// returns 6.5``````

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 = umidmean( sorted, true );
// returns 6.5``````

## Examples

``````var data = new Array( 100 );

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

console.log( umidmean( 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 upper range. If the input `array` is already sorted in ascending order, the function is `O(m)`.
The upper midmean includes the values located between but not including the first and third quartiles of the upper range. In the following examples, the values included in the upper midmean are in bold.

## 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``