time-to-botec/squiggle/node_modules/@stdlib/stats/fligner-test/lib/median.js
NunoSempere b6addc7f05 feat: add the node modules
Necessary in order to clearly see the squiggle hotwiring.
2022-12-03 12:44:49 +00:00

81 lines
1.6 KiB
JavaScript

/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MODULES //
var floor = require( '@stdlib/math/base/special/floor' );
// FUNCTIONS //
/**
* Comparator function used to sort values in ascending order.
*
* @private
* @param {number} a - first number
* @param {number} b - second number
* @returns {number} difference between `a` and `b`
*/
function ascending( a, b ) {
return a - b;
}
// MAIN //
/**
* Computes the median of an array.
*
* @param {Array} arr - input array
* @returns {number} median value
*/
function median( arr ) {
var len = arr.length;
var id;
var d;
var i;
if ( !len ) {
return null;
}
// Copy and sort data in ascending order:
d = [];
for ( i = 0; i < len; i++ ) {
d.push( arr[ i ] );
}
d.sort( ascending );
// Get the middle index:
id = floor( len / 2 );
if ( len % 2 ) {
// The number of elements is not evenly divisible by two, hence we have a middle index:
return d[ id ];
}
// Even number of elements, so must take the mean of the two middle values:
return ( d[ id-1 ] + d[ id ] ) / 2.0;
}
// EXPORTS //
module.exports = median;