104 lines
2.2 KiB
JavaScript
104 lines
2.2 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2020 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var Int32Array = require( '@stdlib/array/int32' );
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// FUNCTIONS //
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/**
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* Returns a comparison result. If `-1`, `a` comes before `b`. If `1`, `b` comes before `a`. If `0`, the order stays the same.
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*
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* @private
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* @param {number} a - first number
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* @param {number} b - second number
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* @returns {boolean} comparison result
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*/
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function ascending( a, b ) {
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if ( a < b ) {
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return -1;
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}
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if ( a > b ) {
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return 1;
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}
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return 0;
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}
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/**
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* Returns a comparison result. If `-1`, `a` comes before `b`. If `1`, `b` comes before `a`. If `0`, the order stays the same.
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*
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* @private
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* @param {number} a - first number
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* @param {number} b - second number
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* @returns {boolean} comparison result
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*/
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function descending( a, b ) {
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if ( a < b ) {
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return 1;
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}
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if ( a > b ) {
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return -1;
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}
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return 0;
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}
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// MAIN //
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/**
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* Returns a permutation which rearranges input array.
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*
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* @private
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* @param {ArrayLike} x - input array-like object
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* @param {boolean} invert - controls whether to permutation that sorts input array in descending order
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* @returns {Array} permutation array
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*/
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function order( x, invert ) {
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var comparator;
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var arr;
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var i;
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comparator = ( invert ) ? descending : ascending;
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arr = new Int32Array( x.length );
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for ( i = 0; i < x.length; i++ ) {
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arr[ i ] = i;
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}
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return arr.sort( compare );
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/**
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* Compare the elements of the input array.
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*
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* @private
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* @param {number} a - first number
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* @param {number} b - second number
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* @returns {boolean} comparison result
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*/
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function compare( a, b ) {
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return comparator( x[a], x[b] );
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}
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}
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// EXPORTS //
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module.exports = order;
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