84 lines
2.0 KiB
JavaScript
84 lines
2.0 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2021 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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// MAIN //
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/**
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* Applies a unary function to each element retrieved from a strided input array according to a callback function and assigns each result to an element in a strided output array.
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*
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* @param {NonNegativeInteger} N - number of indexed elements
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* @param {Collection} x - input array/collection
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* @param {integer} strideX - `x` stride length
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* @param {Collection} y - destination array/collection
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* @param {integer} strideY - `y` stride length
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* @param {Function} fcn - unary function to apply to callback return values
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* @param {Callback} clbk - callback
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* @param {*} [thisArg] - callback execution context
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* @returns {Collection} `y`
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*
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* @example
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* var abs = require( '@stdlib/math/base/special/abs' );
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*
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* function accessor( v ) {
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* return v * 2.0;
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* }
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*
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* var x = [ 1.0, -2.0, 3.0, -4.0, 5.0 ];
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* var y = [ 0.0, 0.0, 0.0, 0.0, 0.0 ];
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*
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* mapBy( x.length, x, 1, y, 1, abs, accessor );
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*
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* console.log( y );
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* // => [ 2.0, 4.0, 6.0, 8.0, 10.0 ]
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*/
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function mapBy( N, x, strideX, y, strideY, fcn, clbk, thisArg ) {
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var ix;
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var iy;
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var v;
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var i;
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if ( N <= 0 ) {
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return y;
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}
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if ( strideX < 0 ) {
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ix = (1-N) * strideX;
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} else {
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ix = 0;
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}
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if ( strideY < 0 ) {
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iy = (1-N) * strideY;
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} else {
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iy = 0;
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}
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for ( i = 0; i < N; i++ ) {
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v = clbk.call( thisArg, x[ ix ], i, ix, iy, x, y );
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if ( v !== void 0 ) {
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y[ iy ] = fcn( v );
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}
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ix += strideX;
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iy += strideY;
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}
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return y;
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}
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// EXPORTS //
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module.exports = mapBy;
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