at2d

Return an element from a two-dimensional nested array.

Installation

npm install @stdlib/array-base-at2d

Usage

var at2d = require( '@stdlib/array-base-at2d' );

at2d( x, i0, i1 )

Return an element from a two-dimensional nested array.

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

var out = at2d( x, 0, 1 );
// returns 2

out = at2d( x, 1, 0 );
// returns 3

The function accepts the following arguments:

• x: two-dimensional nested input array.
• i0: first dimension index.
• i1: second dimension index.

Notes

• Negative indices are resolved relative to the last element along the respective dimension, with the last element corresponding to -1.
• If provided out-of-bounds indices, the function always returns undefined.

Examples

var papply = require( '@stdlib/utils-papply' );
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var filled2dBy = require( '@stdlib/array-base-filled2d-by' );
var binary2d = require( '@stdlib/array-base-binary2d' );
var zeros2d = require( '@stdlib/array-base-zeros2d' );
var at2d = require( '@stdlib/array-base-at2d' );

var shape = [ 3, 3 ];

// Define a nested input array:
var x = filled2dBy( shape, discreteUniform( -100, 100 ) );
console.log( x );

// Define arrays containing random index values:
var i0 = filled2dBy( shape, discreteUniform( -shape[0], shape[0]-1 ) );
console.log( i0 );

var i1 = filled2dBy( shape, discreteUniform( -shape[1], shape[1]-1 ) );
console.log( i1 );

// Define an output array:
var out = zeros2d( shape );
console.log( out );

// Fill the output array with randomly selected values from the input array:
binary2d( [ i0, i1, out ], shape, papply( at2d, x ) );
console.log( out );

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

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.