Harmonic Mean
Computes the harmonic mean over an array of values.
Installation
$ npm install compute-hmean
Usage
The use the module,
var hmean = ;
hmean( arr )
Computes the harmonic mean.
var data = 1 5 3 4 16 ;var mu = ;// returns ~2.7088
Note: only calculate the harmonic mean for positive, real numbers.
If an array
contains negative numbers, the harmonic mean is nonsensical. For example, consider x = [ 3, -3, 4 ]
. The harmonic mean of x
is 12
, while the arithmetic mean is 1.33333...
. The harmonic mean should never be greater than the arithmetic mean.
Similarly, if an array
contains zero values, the harmonic mean is also zero: 1/0 --> infinity
and 1/infinity --> 0
. For example, consider x = [ 0, 100, 1000, 10000 ]
. Using the textbook definition of the harmonic mean, the mean would be 0
, which, given x
, does not make sense.
If an array
contains elements less than or equal to 0
, the function returns NaN
.
Examples
var hmean = ;var data = 1000 ;for var i = 0; i < datalength; i++data i = Math * 100;console;
To run the example code from the top-level application directory,
$ node ./examples/index.js
Notes
For arrays exceeding memory constraints, you are encouraged to use streams; see flow-hmean.
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.