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Apply a unary function to a double-precision floating-point strided input array according to a strided mask array and assign results to a double-precision floating-point strided output array.
import dmskmap from 'https://cdn.jsdelivr.net/gh/stdlib-js/strided-base-dmskmap@deno/mod.js';You can also import the following named exports from the package:
import { ndarray } from 'https://cdn.jsdelivr.net/gh/stdlib-js/strided-base-dmskmap@deno/mod.js';Applies a unary function to a double-precision floating-point strided input array according to a strided mask array and assigns results to a double-precision floating-point strided output array.
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import abs from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-abs@deno/mod.js';
var x = new Float64Array( [ -2.0, 1.0, -3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0, 1, 1, 0 ] );
// Compute the absolute values in-place:
dmskmap( x.length, x, 1, m, 1, x, 1, abs );
// x => <Float64Array>[ 2.0, 1.0, -3.0, 5.0, 4.0, 0.0, -1.0, 3.0 ]The function accepts the following arguments:
- N: number of indexed elements.
- x: input
Float64Array. - strideX: index increment for
x. - mask: mask
Uint8Array. - strideMask: index increment for
mask. - y: output
Float64Array. - strideY: index increment for
y. - fcn: function to apply.
The N and stride parameters determine which elements in the strided arrays 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,
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import abs from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-abs@deno/mod.js';
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0, 1 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmskmap( 3, x, 2, m, 2, y, -1, abs );
// y => <Float64Array>[ 5.0, 0.0, 1.0, 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';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import abs from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-abs@deno/mod.js';
// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var m0 = new Uint8Array( [ 0, 0, 1, 0, 0, 1 ] );
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 m1 = new Uint8Array( m0.buffer, m0.BYTES_PER_ELEMENT*3 ); // start at 4th element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
dmskmap( 3, x1, -2, m1, 1, y1, 1, abs );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 0.0 ]Applies a unary function to a double-precision floating-point strided input array according to a strided mask array and assigns results to a double-precision floating-point strided output array using alternative indexing semantics.
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import abs from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-abs@deno/mod.js';
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmskmap.ndarray( x.length, x, 1, 0, m, 1, 0, y, 1, 0, abs );
// y => <Float64Array>[ 1.0, 2.0, 0.0, 4.0, 5.0 ]The function accepts the following additional arguments:
- offsetX: starting index for
x. - offsetMask: starting index for
mask. - 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 in reverse order,
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import abs from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-abs@deno/mod.js';
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0, 1 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmskmap.ndarray( 3, x, 2, 1, m, 2, 1, y, -1, y.length-1, abs );
// y => <Float64Array>[ 0.0, 0.0, 0.0, 0.0, 4.0, 2.0 ]import round from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-round@deno/mod.js';
import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@deno/mod.js';
import bernoulli from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-bernoulli@deno/mod.js';
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';
import Uint8Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-uint8@deno/mod.js';
import dmskmap from 'https://cdn.jsdelivr.net/gh/stdlib-js/strided-base-dmskmap@deno/mod.js';
function scale( x ) {
return x * 10.0;
}
var x = new Float64Array( 10 );
var m = new Uint8Array( x.length );
var y = new Float64Array( x.length );
var i;
for ( i = 0; i < x.length; i++ ) {
x[ i ] = round( (randu()*200.0) - 100.0 );
m[ i ] = bernoulli( 0.2 );
}
console.log( x );
console.log( m );
console.log( y );
dmskmap.ndarray( x.length, x, 1, 0, m, 1, 0, y, -1, y.length-1, scale );
console.log( y );@stdlib/strided-base/dmap: apply a unary function to a double-precision floating-point strided input array and assign results to a double-precision floating-point strided output array.@stdlib/strided-base/dmskmap2: apply a binary function to double-precision floating-point strided input arrays according to a strided mask array and assign results to a double-precision floating-point strided output array.@stdlib/strided-base/mskunary: apply a unary callback to elements in a strided input array according to elements in a strided mask array and assign results to elements in a strided output array.@stdlib/strided-base/smskmap: apply a unary function to a single-precision floating-point strided input array according to a strided mask array and assign results to a single-precision floating-point strided output array.
This package is part of stdlib, a standard library with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
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