All files / map-by/lib accessors.ndarray.js

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/**
* @license Apache-2.0
*
* Copyright (c) 2021 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
 
'use strict';
 
// MAIN //
 
/**
* Applies a unary function to each element retrieved from a strided input array according to a callback function and assigns results to a strided output array.
*
* @private
* @param {NonNegativeInteger} N - number of indexed elements
* @param {Collection} x - input array/collection
* @param {integer} strideX - `x` stride length
* @param {NonNegativeInteger} offsetX - starting `x` index
* @param {Function} xget - accessor for retrieving elements in `x`
* @param {Collection} y - destination array/collection
* @param {integer} strideY - `y` stride length
* @param {NonNegativeInteger} offsetY - starting `y` index
* @param {Function} yset - accessor for setting elements in `x`
* @param {Function} fcn - unary function to apply to callback return values
* @param {Callback} clbk - callback
* @param {*} [thisArg] - callback execution context
* @returns {Collection} `y`
*
* @example
* var abs = require( '@stdlib/math/base/special/abs' );
*
* function accessor( v ) {
*     return v;
* }
*
* function xget( buf, idx ) {
*     return buf[ idx ] * 2.0;
* }
*
* function yset( buf, idx, value ) {
*     buf[ idx ] = value;
* }
*
* var x = [ 1.0, -2.0, 3.0, -4.0, 5.0 ];
* var y = [ 0.0, 0.0, 0.0, 0.0, 0.0 ];
*
* mapBy( x.length, x, 1, 0, xget, y, 1, 0, yset, abs, accessor );
*
* console.log( y );
* // => [ 2.0, 4.0, 6.0, 8.0, 10.0 ]
*/
function mapBy( N, x, strideX, offsetX, xget, y, strideY, offsetY, yset, fcn, clbk, thisArg ) { // eslint-disable-line max-len, max-params
	var ix;
	var iy;
	var v;
	var i;

	if ( N <= 0 ) {
		return y;
	}
	ix = offsetX;
	iy = offsetY;
	for ( i = 0; i < N; i++ ) {
		v = clbk.call( thisArg, xget( x, ix ), i, [ ix, iy ], [ x, y ] );
		if ( v !== void 0 ) {
			yset( y, iy, fcn( v ) );
		}
		ix += strideX;
		iy += strideY;
	}
	return y;
}
 
 
// EXPORTS //
 
module.exports = mapBy;