function mapBy( N, x, strideX, y, strideY, fcn, clbk, thisArg ) {
	var xget;
	var yset;

	if ( isAccessorArray( x ) ) {
		xget = accessorGetter( dtype( x ) );
	}
	if ( isAccessorArray( y ) ) {
		yset = accessorSetter( dtype( y ) );
	}
	if ( xget || yset ) {
		xget = xget || getter( dtype( x ) );
		yset = yset || setter( dtype( y ) );
		return accessors( N, x, strideX, xget, y, strideY, yset, fcn, clbk, thisArg ); // eslint-disable-line max-len
	}
	return strided( N, x, strideX, y, strideY, fcn, clbk, thisArg );
}
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.

@param {NonNegativeInteger} N - number of indexed elements
@param {Collection} x - input array/collection
@param {integer} strideX - `x` stride length
@param {Collection} y - destination array/collection
@param {integer} strideY - `y` stride length
@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 * 2.0;
}

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, y, 1, abs, accessor );

console.log( y );
// => [ 2.0, 4.0, 6.0, 8.0, 10.0 ]