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Compute the absolute value of each element retrieved from a strided input array via a callback function and assign each result to an element in a strided output array.
import absBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-strided-special-abs-by@deno/mod.js';You can also import the following named exports from the package:
import { ndarray } from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-strided-special-abs-by@deno/mod.js';Computes the absolute value of each element retrieved from a strided input array x via a callback function and assigns each result to an element in a strided output array y.
function accessor( v ) {
return v * 2.0;
}
var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];
var y = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];
absBy( x.length, x, 1, y, 1, accessor );
// y => [ 4.0, 2.0, 6.0, 10.0, 8.0, 0.0, 2.0, 6.0 ]The function accepts the following arguments:
- N: number of indexed elements.
- x: input
Array,typed array, or an array-like object (excluding strings and functions). - strideX: index increment for
x. - y: output
Array,typed array, or an array-like object (excluding strings and functions). - strideY: index increment for
y. - clbk: callback function.
- thisArg: execution context (optional).
The invoked callback function is provided six arguments:
- value: input array element.
- idx: iteration index (zero-based).
- xi: input array strided index (
offsetX + idx*strideX). - yi: output array strided index (
offsetY + idx*strideY). - x: input array/collection.
- y: output array/collection.
To set the callback execution context, provide a thisArg.
function accessor( v ) {
this.count += 1;
return v * 2.0;
}
var context = {
'count': 0
};
var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];
var y = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];
absBy( x.length, x, 1, y, 1, accessor, context );
// y => [ 4.0, 2.0, 6.0, 10.0, 8.0, 0.0, 2.0, 6.0 ]
var cnt = context.count;
// returns 8The N and stride parameters determine which elements in x and y are accessed at runtime. For example, to index every other value in x and to index the first N elements of y in reverse order,
function accessor( v ) {
return v * 2.0;
}
var x = [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ];
var y = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];
absBy( 3, x, 2, y, -1, accessor );
// y => [ 10.0, 6.0, 2.0, 0.0, 0.0, 0.0 ]Note that indexing is relative to the first index. To introduce an offset, use typed array views.
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
function accessor( v ) {
return v * 2.0;
}
// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
absBy( 3, x1, -2, y1, 1, accessor );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, 12.0, 8.0, 4.0 ]Computes the absolute value of each element retrieved from a strided input array x via a callback function and assigns each result to an element in a strided output array y using alternative indexing semantics.
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 ];
absBy.ndarray( x.length, x, 1, 0, y, 1, 0, accessor );
// y => [ 2.0, 4.0, 6.0, 8.0, 10.0 ]The function accepts the following additional arguments:
- offsetX: starting index for
x. - offsetY: starting index for
y.
While typed array views mandate a view offset based on the underlying buffer, the offsetX and offsetY parameters support indexing semantics based on starting indices. For example, to index every other value in x starting from the second value and to index the last N elements in y,
function accessor( v ) {
return v * 2.0;
}
var x = [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ];
var y = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];
absBy.ndarray( 3, x, 2, 1, y, -1, y.length-1, accessor );
// y => [ 0.0, 0.0, 0.0, 12.0, 8.0, 4.0 ]-
If a provided callback function does not return any value (or equivalently, explicitly returns
undefined), the value is ignored.function accessor() { // No-op... } var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ]; var y = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]; absBy( x.length, x, 1, y, 1, accessor ); // y => [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ]
var uniform = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-uniform' ).factory;
import filledarray from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-filled@deno/mod.js';
import filledarrayBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-filled-by@deno/mod.js';
import absBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-strided-special-abs-by@deno/mod.js';
function accessor( v, i ) {
if ( (i%3) === 0 ) {
// Simulate a "missing" value...
return;
}
return v;
}
var x = filledarrayBy( 10, 'generic', uniform( -100.0, 100.0 ) );
console.log( x );
var y = filledarray( null, 10, 'generic' );
console.log( y );
absBy.ndarray( x.length, x, 1, 0, y, -1, y.length-1, accessor );
console.log( y );@stdlib/math-strided/special/abs: compute the absolute value for each element in a strided array.@stdlib/math-strided/special/abs2-by: compute the squared absolute value of each element retrieved from an input strided array via a callback function.
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