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https://github.com/stdlib-js/ndarray-base-vind2bind

Convert a linear index in an array view to a linear index in an underlying data buffer.
https://github.com/stdlib-js/ndarray-base-vind2bind

array base index javascript linear multidimensional ndarray node node-js nodejs offset shape stdlib strides types util utilities utility utils view

Last synced: 10 days ago
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Convert a linear index in an array view to a linear index in an underlying data buffer.

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README 

        



  

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# vind2bind



[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] 



> Convert a linear index in an array view to a linear index in an underlying data buffer.



## Installation



```bash

npm install @stdlib/ndarray-base-vind2bind

```



Alternatively,



-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).

-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).

-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).



The [branches.md][branches-url] 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



```javascript

var vind2bind = require( '@stdlib/ndarray-base-vind2bind' );

```



#### vind2bind( shape, strides, offset, order, idx, mode )



Converts a linear index in an array view to a linear index in an underlying data buffer.



```javascript

var shape = [ 3, 3 ];

var order = 'row-major';

var strides = [ -3, 1 ];

var offset = 6;



var idx = vind2bind( shape, strides, offset, order, 1, 'throw' );

// returns 7

```



The function supports the following modes:



-   **throw**: specifies that the function should throw an error when a linear index exceeds array dimensions.

-   **normalize**: specifies that the function should normalize negative linear indices and throw an error when a linear index exceeds array dimensions.

-   **wrap**: specifies that the function should wrap around a linear index exceeding array dimensions using modulo arithmetic.

-   **clamp**: specifies that the function should set a linear index exceeding array dimensions to either `0` (minimum linear index) or the maximum linear index.



```javascript

var shape = [ 2, 2 ];

var order = 'row-major';

var strides = [ -2, 1 ];

var offset = 2;



var idx = vind2bind( shape, strides, offset, order, -2, 'wrap' );

// returns 0



idx = vind2bind( shape, strides, offset, order, 10, 'clamp' );

// returns 1

```



The `order` parameter specifies whether an array is `row-major` (C-style) or `column-major` (Fortran-style).



```javascript

var shape = [ 2, 2 ];

var order = 'column-major';

var strides = [ 1, -2 ];

var offset = 2;



var idx = vind2bind( shape, strides, offset, order, 2, 'throw' );

// returns 0

```



## Examples



```javascript

var shape2strides = require( '@stdlib/ndarray-base-shape2strides' );

var strides2offset = require( '@stdlib/ndarray-base-strides2offset' );

var numel = require( '@stdlib/ndarray-base-numel' );

var randu = require( '@stdlib/random-base-randu' );

var vind2bind = require( '@stdlib/ndarray-base-vind2bind' );



// Specify array meta data:

var shape = [ 3, 3, 3 ];

var order = 'row-major';



// Compute array meta data:

var len = numel( shape );

var strides = shape2strides( shape, order );



// Randomly flip the sign of strides...

var i;

for ( i = 0; i < shape.length; i++ ) {

    if ( randu() < 0.5 ) {

        strides[ i ] *= -1;

    }

}



// Compute the underlying data buffer index offset:

var offset = strides2offset( shape, strides );



// Print array info:

console.log( 'Dims: %s', shape.join( 'x' ) );

console.log( 'Strides: %s', strides.join( ',' ) );

console.log( 'Offset: %d', offset );



// For each view index, determine the corresponding index into an array's underlying data buffer...

var ind;

for ( i = 0; i < len; i++ ) {

    ind = vind2bind( shape, strides, offset, order, i, 'throw' );

    console.log( 'view[%d] => buffer[%d]', i, ind );

}

```



* * *



## Notice



This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].



#### Community



[![Chat][chat-image]][chat-url]



---



## License



See [LICENSE][stdlib-license].



## Copyright



Copyright © 2016-2024. The Stdlib [Authors][stdlib-authors].



[npm-image]: http://img.shields.io/npm/v/@stdlib/ndarray-base-vind2bind.svg

[npm-url]: https://npmjs.org/package/@stdlib/ndarray-base-vind2bind



[test-image]: https://github.com/stdlib-js/ndarray-base-vind2bind/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/ndarray-base-vind2bind/actions/workflows/test.yml?query=branch:main



[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/ndarray-base-vind2bind/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/ndarray-base-vind2bind?branch=main



[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg

[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im



[stdlib]: https://github.com/stdlib-js/stdlib



[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors



[umd]: https://github.com/umdjs/umd

[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules



[deno-url]: https://github.com/stdlib-js/ndarray-base-vind2bind/tree/deno

[deno-readme]: https://github.com/stdlib-js/ndarray-base-vind2bind/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/ndarray-base-vind2bind/tree/umd

[umd-readme]: https://github.com/stdlib-js/ndarray-base-vind2bind/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/ndarray-base-vind2bind/tree/esm

[esm-readme]: https://github.com/stdlib-js/ndarray-base-vind2bind/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/ndarray-base-vind2bind/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/ndarray-base-vind2bind/main/LICENSE