Computes a quantile for a numeric array.
npm install compute-quantileQuantile
===
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> Computes a quantile for a numeric array.
This module determines the nearest rank and returns the array value corresponding to that rank.
This module does __not__ currently support multiple interpolation methods, and instead uses a standard elementary method for estimating the quantile.
`` bash`
$ npm install compute-quantile
For use in the browser, use browserify.
To use the module,
` javascript`
var quantile = require( 'compute-quantile' );
#### quantile( arr, p[, opts] )
Given a probability 0 <= p <= 1, computes the quantile for an input array.
` javascript
var unsorted = [ 4, 3, 5, 1, 2 ];
var q = quantile( unsorted, 0.25 );
// returns 2
`
If the input array is already sorted in __ascending__ order, you can set the sorted option to true.
` javascript
var sorted = [ 1, 2, 3, 4, 5 ];
var q = quantile( sorted, 0.25, { 'sorted': true } );
// returns 2
`
` javascript
var quantile = require( 'compute-quantile' );
// Simulate some data...
var data = new Array( 1000 );
for ( var i = 0, len = data.length; i < len; i++ ) {
data[ i ] = Math.round( Math.random()*1000 );
}
// Compute the p-quantile for p = 0.5 (median):
console.log( quantile( data, 0.5 ) );
`
To run the example code from the top-level application directory,
` bash`
$ node ./examples/index.js
The probability p is equal to k / q, where q is the total number of quantiles and k is the _k_ th quantile.
If the input array is not sorted in __ascending__ order, the function is O( N log(N) ), where N is the input array length. If the array is sorted, the function is O(1).
Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:
` bash`
$ make test
All new feature development should have corresponding unit tests to validate correct functionality.
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:
` bash`
$ make test-cov
Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,
` bash``
$ make view-cov
---
Copyright © 2014. Athan Reines.
[npm-image]: http://img.shields.io/npm/v/compute-quantile.svg
[npm-url]: https://npmjs.org/package/compute-quantile
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[travis-url]: https://travis-ci.org/compute-io/quantile
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[dependencies-url]: https://david-dm.org/compute-io/quantile
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[dev-dependencies-url]: https://david-dm.org/dev/compute-io/quantile
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[github-issues-url]: https://github.com/compute-io/quantile/issues