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writeDataView

Copy elements from an input strided array to elements in a strided DataView.

Installation

npm install @stdlib/strided-base-write-dataview

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var writeDataView = require( '@stdlib/strided-base-write-dataview' );

writeDataView( N, x, strideX, view, strideView, littleEndian )

Copies elements from an input strided array to elements in a strided DataView.

var ArrayBuffer = require( '@stdlib/array-buffer' );
var DataView = require( '@stdlib/array-dataview' );

var x = [ 1.0, 2.0, 3.0, 4.0 ];

var buf = new ArrayBuffer( 32 );
var view = new DataView( buf );

var out = writeDataView( 4, x, 1, view, 8, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 0, true );
// returns 1.0

v = view.getFloat64( 8, true );
// returns 2.0

The function accepts the following arguments:

• N: number of indexed elements.
• x: input strided array.
• strideX: index increment for x.
• view: output DataView.
• strideView: index increment (in bytes) for view.
• littleEndian: boolean indicating whether to store values in little-endian format.

The N and stride parameters determine which elements in x and view are accessed at runtime. For example, to index every other value in x and to index the first N elements of view in reverse order,

var ArrayBuffer = require( '@stdlib/array-buffer' );
var DataView = require( '@stdlib/array-dataview' );

var x = [ 1.0, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0, 0.0 ];

var buf = new ArrayBuffer( 64 );
var view = new DataView( buf );

var out = writeDataView( 4, x, 2, view, -8, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 0, true );
// returns 4.0

v = view.getFloat64( 8, true );
// returns 3.0

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

var ArrayBuffer = require( '@stdlib/array-buffer' );
var DataView = require( '@stdlib/array-dataview' );
var Float32Array = require( '@stdlib/array-float32' );

// Initial array:
var x0 = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

// Create an offset view:
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Create an output DataView:
var buf = new ArrayBuffer( 64 );
var view = new DataView( buf );

var out = writeDataView( 4, x1, 1, view, 8, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat32( 0, true );
// returns 2.0

v = view.getFloat32( 8, true );
// returns 3.0

writeDataView.ndarray( N, x, strideX, offsetX, view, strideView, offsetView, littleEndian )

Copies elements from an input strided array to elements in a strided DataView using alternative indexing semantics.

var ArrayBuffer = require( '@stdlib/array-buffer' );
var DataView = require( '@stdlib/array-dataview' );

var x = [ 1.0, 2.0, 3.0, 4.0 ];

var buf = new ArrayBuffer( 32 );
var view = new DataView( buf );

var out = writeDataView.ndarray( 4, x, 1, 0, view, 8, 0, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 0, true );
// returns 1.0

The function accepts the following additional arguments:

• offsetX: starting index for x.
• offsetView: starting index (in bytes) for view.

While typed array views mandate a view offset based on the underlying buffer, the offset 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 view in reverse order,

var ArrayBuffer = require( '@stdlib/array-buffer' );
var DataView = require( '@stdlib/array-dataview' );

var x = [ 0.0, 1.0, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0 ];

var buf = new ArrayBuffer( 64 );
var view = new DataView( buf );

var out = writeDataView.ndarray( 4, x, 2, 1, view, -8, 56, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 32, true );
// returns 4.0

v = view.getFloat64( 40, true );
// returns 3.0

Examples

var ArrayBuffer = require( '@stdlib/array-buffer' );
var DataView = require( '@stdlib/array-dataview' );
var typedarray = require( '@stdlib/array-typed' );
var bytesPerElement = require( '@stdlib/ndarray-base-bytes-per-element' );
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var IS_LITTLE_ENDIAN = require( '@stdlib/assert-is-little-endian' );
var logEach = require( '@stdlib/console-log-each' );
var writeDataView = require( '@stdlib/strided-base-write-dataview' );

// Specify the array data type:
var dtype = 'float64';

// Resolve the number of bytes per element:
var nbytes = bytesPerElement( dtype );

// Generate an array of random numbers:
var x = discreteUniform( 10, 0, 100, {
    'dtype': dtype
});

// Create a DataView:
var buf = new ArrayBuffer( x.length*nbytes );
var view = new DataView( buf );

// Copy the numbers to the DataView:
writeDataView( x.length, x, 1, view, nbytes, IS_LITTLE_ENDIAN );

// Create a view of the DataView:
var y = typedarray( view.buffer, dtype );

// Print the results:
logEach( '%d -> %d', x, y );

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, 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.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.