About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

flatten2dBy

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

> Flatten a two-dimensional nested array according to a callback function.

Installation

``bash npm install @stdlib/array-base-flatten2d-by`

`Usage`

`javascript var flatten2dBy = require( '@stdlib/array-base-flatten2d-by' );`

#### flatten2dBy( x, shape, colexicographic, clbk\[, thisArg] )

Flattens a two-dimensional nested array according to a callback function.

`javascript function scale( v ) { return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten2dBy( x, [ 2, 2 ], false, scale ); // returns [ 2, 4, 6, 8 ]`

To flatten in colexicographic order, provide a third argument equal to true.

`javascript function scale( v ) { return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten2dBy( x, [ 2, 2 ], true, scale ); // returns [ 2, 6, 4, 8 ]`

To set the callback execution context, provide a thisArg argument.

`javascript function scale( v ) { this.count += 1; return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ]; var ctx = { 'count': 0 };

var out = flatten2dBy( x, [ 2, 2 ], false, scale, ctx ); // returns [ 2, 4, 6, 8 ]

var count = ctx.count; // returns 4`

#### flatten2dBy.assign( x, shape, colexicographic, out, stride, offset, clbk\[, thisArg] )

Flattens a two-dimensional nested array according to a callback function and assigns elements to a provided output array.

`javascript var Float64Array = require( '@stdlib/array-float64' );

function scale( v ) { return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ]; var out = new Float64Array( 4 );

var y = flatten2dBy.assign( x, [ 2, 2 ], false, out, 1, 0, scale ); // returns [ 2, 4, 6, 8 ]

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

y = flatten2dBy.assign( x, [ 2, 2 ], true, out, 1, 0, scale ); // returns [ 2, 6, 4, 8 ]`

`Notes`

- A callback function is provided the following arguments:

- value: nested array element. - indices: element indices (in lexicographic order). - arr: the input array.

- Both functions assume that all nested arrays have the same length (i.e., the input array is not a ragged array).

`Examples`

`javascript var naryFunction = require( '@stdlib/utils-nary-function' ); var abs = require( '@stdlib/math-base-special-abs' ); var flatten2dBy = require( '@stdlib/array-base-flatten2d-by' );

var fcn = naryFunction( abs, 1 );

var x = [ [ -1, -2, -3, -4 ], [ -5, -6, -7, -8 ], [ -9, -10, -11, -12 ], [ -13, -14, -15, -16 ] ];

var out = flatten2dBy( x, [ 0, 0 ], false, fcn ); // returns []

out = flatten2dBy( x, [ 0, 0 ], true, fcn ); // returns []

out = flatten2dBy( x, [ 1, 1 ], false, fcn ); // returns [ 1 ]

out = flatten2dBy( x, [ 1, 1 ], true, fcn ); // returns [ 1 ]

out = flatten2dBy( x, [ 2, 2 ], false, fcn ); // returns [ 1, 2, 5, 6 ]

out = flatten2dBy( x, [ 2, 2 ], true, fcn ); // returns [ 1, 5, 2, 6 ]

out = flatten2dBy( x, [ 3, 3 ], false, fcn ); // returns [ 1, 2, 3, 5, 6, 7, 9, 10, 11 ]

out = flatten2dBy( x, [ 3, 3 ], true, fcn ); // returns [ 1, 5, 9, 2, 6, 10, 3, 7, 11 ]

out = flatten2dBy( x, [ 4, 4 ], false, fcn ); // returns [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ]

out = flatten2dBy( x, [ 4, 4 ], true, fcn ); // returns [ 1, 5, 9, 13, 2, 6, 10, 14, 3, 7, 11, 15, 4, 8, 12, 16 ]`

*

`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`

[npm-image]: http://img.shields.io/npm/v/@stdlib/array-base-flatten2d-by.svg [npm-url]: https://npmjs.org/package/@stdlib/array-base-flatten2d-by

[test-image]: https://github.com/stdlib-js/array-base-flatten2d-by/actions/workflows/test.yml/badge.svg?branch=v0.2.3 [test-url]: https://github.com/stdlib-js/array-base-flatten2d-by/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/array-base-flatten2d-by/main.svg [coverage-url]: https://codecov.io/github/stdlib-js/array-base-flatten2d-by?branch=main

[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg [chat-url]: https://stdlib.zulipchat.com

[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/array-base-flatten2d-by/tree/deno [deno-readme]: https://github.com/stdlib-js/array-base-flatten2d-by/blob/deno/README.md [umd-url]: https://github.com/stdlib-js/array-base-flatten2d-by/tree/umd [umd-readme]: https://github.com/stdlib-js/array-base-flatten2d-by/blob/umd/README.md [esm-url]: https://github.com/stdlib-js/array-base-flatten2d-by/tree/esm [esm-readme]: https://github.com/stdlib-js/array-base-flatten2d-by/blob/esm/README.md [branches-url]: https://github.com/stdlib-js/array-base-flatten2d-by/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/array-base-flatten2d-by/main/LICENSE

[@stdlib/array/base/flatten2d]: https://www.npmjs.com/package/@stdlib/array-base-flatten2d


  
    About stdlib...
  

  We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

  The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

  When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

  To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

`flatten2dBy`

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

> Flatten a two-dimensional nested array according to a callback function.

`Installation`

``bash npm install @stdlib/array-base-flatten2d-by `

`Usage`

`javascript var flatten2dBy = require( '@stdlib/array-base-flatten2d-by' ); `

#### flatten2dBy( x, shape, colexicographic, clbk\[, thisArg] )

Flattens a two-dimensional nested array according to a callback function.

`javascript function scale( v ) { return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten2dBy( x, [ 2, 2 ], false, scale ); // returns [ 2, 4, 6, 8 ] `

To flatten in colexicographic order, provide a third argument equal to true.

`javascript function scale( v ) { return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten2dBy( x, [ 2, 2 ], true, scale ); // returns [ 2, 6, 4, 8 ] `

To set the callback execution context, provide a thisArg argument.

`javascript function scale( v ) { this.count += 1; return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ]; var ctx = { 'count': 0 };

var out = flatten2dBy( x, [ 2, 2 ], false, scale, ctx ); // returns [ 2, 4, 6, 8 ]

var count = ctx.count; // returns 4 `

#### flatten2dBy.assign( x, shape, colexicographic, out, stride, offset, clbk\[, thisArg] )

Flattens a two-dimensional nested array according to a callback function and assigns elements to a provided output array.

`javascript var Float64Array = require( '@stdlib/array-float64' );

function scale( v ) { return v * 2; }

var x = [ [ 1, 2 ], [ 3, 4 ] ]; var out = new Float64Array( 4 );

var y = flatten2dBy.assign( x, [ 2, 2 ], false, out, 1, 0, scale ); // returns [ 2, 4, 6, 8 ]

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

y = flatten2dBy.assign( x, [ 2, 2 ], true, out, 1, 0, scale ); // returns [ 2, 6, 4, 8 ] `

`Notes`

- A callback function is provided the following arguments:

- value: nested array element. - indices: element indices (in lexicographic order). - arr: the input array.

- Both functions assume that all nested arrays have the same length (i.e., the input array is not a ragged array).

`Examples`

`javascript var naryFunction = require( '@stdlib/utils-nary-function' ); var abs = require( '@stdlib/math-base-special-abs' ); var flatten2dBy = require( '@stdlib/array-base-flatten2d-by' );