118 lines
3.8 KiB
JavaScript
118 lines
3.8 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 getIndex = require( './../../base/sub2ind' );
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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 subscripts to a linear index.
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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 subscript exceeds array dimensions.
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* - `wrap`: wrap around subscripts exceeding array dimensions using modulo arithmetic.
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* - `clamp`: set subscripts exceeding array dimensions to either `0` (minimum index) or the maximum index along a particular dimension.
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*
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* - If provided fewer modes than dimensions, the function recycles modes using modulo arithmetic.
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*
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*
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* @param {NonNegativeIntegerArray} shape - array shape
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* @param {...integer} i - subscripts
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* @param {Options} [options] - function options
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* @param {(StringArray|string)} [options.mode=["throw"]] - specifies how to handle subscripts which exceed 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} first argument must be an array-like object containing nonnegative integers
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* @throws {TypeError} subscripts 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 subscripts which do not exceed array dimensions
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* @throws {RangeError} number of subscripts much match the number of dimensions
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* @returns {NonNegativeInteger} linear index
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*
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* @example
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* var i = sub2ind( [ 3, 3, 3 ], 1, 2, 2 );
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* // returns 17
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*/
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function sub2ind() {
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var options;
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var shape;
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var ndims;
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var args;
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var opts;
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var err;
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var len;
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var i;
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var j;
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shape = arguments[ 0 ];
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if ( !isNonNegativeIntegerArray( shape ) ) {
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throw new TypeError( 'invalid argument. First argument must be an array-like object containing nonnegative integers. Value: `' + shape + '`.' );
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}
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len = arguments.length;
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ndims = shape.length;
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opts = {};
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opts.mode = defaults.mode.slice();
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opts.order = defaults.order;
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if ( len > ndims+1 ) {
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j = len - 1;
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options = arguments[ j ];
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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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} else {
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j = len;
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}
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i = 1;
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if ( j-i !== ndims ) {
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throw new RangeError( 'invalid argument. Number of provided subscripts must match the number of dimensions. ndims: ' + ndims + '. Number of subscripts: ' + (j-i) + '.' );
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}
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args = new Array( ndims+4 );
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args[ 0 ] = shape;
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args[ 1 ] = shape2strides( shape, opts.order );
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args[ 2 ] = 0; // strides are positive, so offset is always zero
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for ( ; i < j; i++ ) {
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if ( !isInteger( arguments[ i ] ) ) {
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throw new TypeError( 'invalid argument. Subscripts must be integer valued. Argument: ' + i + '. Value: `' + arguments[ i ] + '`.' );
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}
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args[ i+2 ] = arguments[ i ];
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}
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args[ i+2 ] = opts.mode; // i+2 == args.length-1
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return getIndex.apply( null, args );
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}
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// EXPORTS //
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module.exports = sub2ind;
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