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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!

numelDimension

NPM version Build Status Coverage Status

Return the size (i.e., number of elements) of a specified dimension for a provided ndarray.

Usage

import numelDimension from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-numel-dimension@esm/index.mjs';

numelDimension( x, dim )

Returns the size (i.e., number of elements) of a specified dimension for a provided ndarray.

import zeros from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-zeros@esm/index.mjs';

var x = zeros( [ 4, 2, 3 ] );
// returns <ndarray>

var d = numelDimension( x, 0 );
// returns 4

The function accepts the following arguments:

  • x: input ndarray.
  • dim: dimension index. If provided an integer less than zero, the dimension index is resolved relative to the last dimension, with the last dimension corresponding to the value -1.

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">

import zeros from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-zeros@esm/index.mjs';
import slice from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-slice@esm/index.mjs';
import E from 'https://cdn.jsdelivr.net/gh/stdlib-js/slice-multi@esm/index.mjs';
import S from 'https://cdn.jsdelivr.net/gh/stdlib-js/slice-ctor@esm/index.mjs';
import numelDimension from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-numel-dimension@esm/index.mjs';

// Create an array:
var x = zeros( [ 10, 10, 10, 10 ] );
// returns <ndarray>

// Define some slices:
var slices = [
    // :,:,:,:
    E( null, null, null, null ),

    // 5:10,4,2:4,::-1
    E( S( 5, 10 ), 4, S( 2, 4 ), S( null, null, -1 ) ),

    // :,:,2,:
    E( null, null, 2, null ),

    // 1,2,3,:
    E( 1, 2, 3, null ),

    // 1,3,::2,4::2
    E( 1, 3, S( null, null, 2 ), S( 4, null, 2 ) )
];

// Resolve the size of the first dimension for each slice...
var s;
var i;
for ( i = 0; i < slices.length; i++ ) {
    s = slice( x, slices[ i ] );
    console.log( '(%s) => %d', s.shape.join( ',' ), numelDimension( s, 0 ) );
}

</script>
</body>
</html>

Notice

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.

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.