84 lines
1.9 KiB
JavaScript
84 lines
1.9 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;
|
|
}
|
|
|
|
/**
|
|
* Computes a quantile of the values in a numeric array.
|
|
*
|
|
* @private
|
|
* @param {NumericArray} arr - sorted 1d array
|
|
* @param {Probability} p - quantile prob [0,1]
|
|
* @returns {number} quantile
|
|
*/
|
|
function quantile( arr, p ) {
|
|
var len = arr.length;
|
|
var id;
|
|
var h;
|
|
h = ( ( len - 1.0 ) * p ) + 1.0;
|
|
id = floor( h ) - 1.0;
|
|
return arr[ id ] + ( ( h - floor( h ) ) * ( arr[ id + 1 ] - arr[ id ] ) );
|
|
}
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Computes the inter-quartile range for a numeric array.
|
|
*
|
|
* @private
|
|
* @param {NumericArray} data - ndarray like data
|
|
* @param {number} j - column index for which to get the IQR
|
|
* @returns {number} inter-quartile range
|
|
*/
|
|
function iqr( data, j ) {
|
|
// Copy and sort data --> build X
|
|
var arr;
|
|
var i;
|
|
arr = new Array( data.shape[0] );
|
|
for ( i = 0; i < data.shape[0]; i++ ) {
|
|
arr[ i ] = data.get( i, j );
|
|
}
|
|
arr.sort( ascending );
|
|
return quantile( arr, 0.75 ) - quantile( arr, 0.25 );
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = iqr;
|