88 lines
3.1 KiB
JavaScript
88 lines
3.1 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 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 isNonNegativeIntegerArray = require( '@stdlib/assert/is-nonnegative-integer-array' ).primitives;
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var isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
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var shape2strides = require( './../../base/shape2strides' );
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var getSubscripts = require( './../../base/ind2sub' );
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var defaults = require( './defaults.json' );
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var validate = require( './validate.js' );
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// MAIN //
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/**
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* Converts a linear index to an array of subscripts.
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*
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* ## Notes
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*
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* - The function accepts the following "modes":
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*
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* - `throw`: throws an error when a linear index exceeds array dimensions.
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* - `wrap`: wrap around a linear index exceeding array dimensions using modulo arithmetic.
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* - `clamp`: set a linear index exceeding array dimensions to either `0` (minimum linear index) or the maximum linear index.
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*
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*
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* @param {NonNegativeIntegerArray} shape - array shape
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* @param {integer} idx - linear index
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* @param {Options} [options] - function options
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* @param {string} [options.mode="throw"] - specifies how to handle a linear index which exceeds array dimensions
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* @param {string} [options.order="row-major"] - specifies whether an array is row-major (C-style) or column-major (Fortran-style)
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* @throws {TypeError} shape argument must be an array-like object containing nonnegative integers
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* @throws {TypeError} linear index argument must be integer valued
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* @throws {TypeError} options argument must be an object
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* @throws {TypeError} must provide valid options
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* @throws {RangeError} must provide a linear index which does not exceed array dimensions
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* @returns {NonNegativeIntegerArray} subscripts
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*
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* @example
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* var s = ind2sub( [ 3, 3, 3 ], 17 );
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* // returns [ 1, 2, 2 ]
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*/
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function ind2sub( shape, idx, options ) {
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var opts;
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var err;
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opts = {};
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opts.mode = defaults.mode;
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opts.order = defaults.order;
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if ( arguments.length > 2 ) {
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err = validate( opts, options );
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if ( err ) {
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throw err;
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}
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}
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if ( !isNonNegativeIntegerArray( shape ) ) {
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throw new TypeError( 'invalid argument. Shape argument must be an array-like object containing nonnegative integers. Value: `' + shape + '`.' );
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}
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if ( !isInteger( idx ) ) {
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throw new TypeError( 'invalid argument. Linear index argument must be integer valued. Value: `' + idx + '`.' );
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}
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// Note: strides are positive, so offset is always zero
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return getSubscripts( shape, shape2strides( shape, opts.order ), 0, opts.order, idx, opts.mode ); // eslint-disable-line max-len
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}
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// EXPORTS //
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module.exports = ind2sub;
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