compute-gmean
Computes the geometric mean of an array.   Last updated 5 years ago by kgryte .
MIT · Repository · Bugs · Original npm · Tarball · package.json
`\$ cnpm install compute-gmean `
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# Geometric Mean

Computes the geometric mean of an array.

## Installation

``````\$ npm install compute-gmean
``````

## Usage

``````var gmean = require( 'compute-gmean' );
``````

#### gmean( arr[, accessor] )

Computes the geometric mean of an `array`. For numeric `arrays`,

``````var data = [ 1, 5, 2, 3, 7 ];

var mu = gmean( data );
// returns ~2.914
``````

For non-numeric `arrays`, provide an accessor `function` for accessing numeric values

``````var arr = [
{'x':1},
{'x':5},
{'x':2},
{'x':3},
{'x':7}
]:

function getValue( d ) {
return d.x;
}

var value = prod( arr, getvalue );
// returns ~2.194
``````

## Examples

``````var gmean = require( 'compute-gmean' );

var data = new Array( 1000 );
for ( var i = 0; i < data.length; i++ ) {
data[ i ] = Math.random() * 100;
}

console.log( gmean( data ) );
``````

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

``````\$ node ./examples/index.js
``````

## Notes

1. Only calculate the geometric mean of an `array` of positive numbers. The textbook formula for calculating the geometric mean involves taking the product of all `array` elements. If one element is `0`, then the product is `0`, even if all other values are `>>> 0`, yielding a nonsensical geometric mean (and measure of the central tendency). Nonsensical results also arise when an `array` contains negative values leading to a product without positive roots and a geometric mean which does not map to the measure's geometric interpretation. For more information, see Handbook of Parametric and Nonparametric Statistical Procedures: Third Edition by David J. Sheskin.
2. If an `array` contains values less than or equal to `0`, the function returns `NaN`.
3. If provided an empty `array`, the function returns `null`.
4. For arrays exceeding memory constraints, you are encouraged to use streams; see flow-gmean.

## 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
``````

## Current Tags

• 1.1.0                                ...           latest (5 years ago)

## 6 Versions

• 1.1.0                                ...           5 years ago
• 1.0.3                                ...           6 years ago
• 1.0.2                                ...           6 years ago
• 1.0.1                                ...           6 years ago
• 1.0.0                                ...           6 years ago
• 0.0.0                                ...           6 years ago