main.js (1844B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var abs = require( '@stdlib/math/base/special/abs' ); 24 25 26 // MAIN // 27 28 /** 29 * Determines the order of a multidimensional array based on a provided stride array. 30 * 31 * @param {IntegerArray} strides - stride array 32 * @returns {integer} order 33 * 34 * @example 35 * var strides2order = require( '@stdlib/ndarray/base/strides2order' ); 36 * 37 * var order = strides2order( [ 2, 1 ] ); 38 * // returns 1 39 * 40 * order = strides2order( [ 1, 2 ] ); 41 * // returns 2 42 * 43 * order = strides2order( [ 1, 1, 1 ] ); 44 * // returns 3 45 * 46 * order = strides2order( [ 2, 3, 1 ] ); 47 * // returns 0 48 */ 49 function strides2order( strides ) { 50 var column; 51 var ndims; 52 var row; 53 var s1; 54 var s2; 55 var i; 56 57 ndims = strides.length; 58 if ( ndims === 0 ) { 59 return 0|0; // 'none' 60 } 61 column = true; 62 row = true; 63 64 s1 = abs( strides[ 0 ] ); 65 for ( i = 1; i < ndims; i++ ) { 66 s2 = abs( strides[ i ] ); 67 if ( column && s2 < s1 ) { 68 column = false; 69 } else if ( row && s2 > s1 ) { 70 row = false; 71 } 72 if ( row || column ) { 73 s1 = s2; 74 } else { 75 return 0|0; // 'none' 76 } 77 } 78 if ( row && column ) { 79 return 3|0; // 'both' 80 } 81 if ( row ) { 82 return 1|0; // 'row-major' 83 } 84 return 2|0; // 'column-major' 85 } 86 87 88 // EXPORTS // 89 90 module.exports = strides2order;