npm package: @stdlib/stats-array-nanmeanwd
Description: Calculate the arithmetic mean of an array, ignoring NaN values and using Welford's algorithm.
Author: The Stdlib Authors
Latest version: 0.1.1

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>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.</p>
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# nanmeanwd

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

> Calculate the [arithmetic mean][arithmetic-mean] of an array, ignoring `NaN` values and using Welford's algorithm.

<section class="intro">

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/stats-array-nanmeanwd
```

</section>

<section class="usage">

## Usage

```javascript
var nanmeanwd = require( '@stdlib/stats-array-nanmeanwd' );
```

#### nanmeanwd( x )

Computes the [arithmetic mean][arithmetic-mean] of an array, ignoring `NaN` values and using Welford's algorithm.

```javascript
var x = [ 1.0, -2.0, NaN, 2.0 ];

var v = nanmeanwd( x );
// returns ~0.3333
```

The function has the following parameters:

-   **x**: input array.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If provided an empty array, the function returns `NaN`.
-   The function supports array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array-base/accessor`][@stdlib/array/base/accessor]).

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var uniform = require( '@stdlib/random-base-uniform' );
var bernoulli = require( '@stdlib/random-base-bernoulli' );
var filledarrayBy = require( '@stdlib/array-filled-by' );
var nanmeanwd = require( '@stdlib/stats-array-nanmeanwd' );

function rand() {
    if ( bernoulli( 0.8 ) < 1 ) {
        return NaN;
    }
    return uniform( -50.0, 50.0 );
}

var x = filledarrayBy( 10, 'float64', rand );
console.log( x );

var v = nanmeanwd( x );
console.log( v );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

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<section class="main-repo" >

* * *

## 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 &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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[npm-url]: https://npmjs.org/package/@stdlib/stats-array-nanmeanwd

[test-image]: https://github.com/stdlib-js/stats-array-nanmeanwd/actions/workflows/test.yml/badge.svg?branch=v0.1.1
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[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/stats-array-nanmeanwd/main.svg
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[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/stats-array-nanmeanwd/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-array-nanmeanwd/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-array-nanmeanwd/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-array-nanmeanwd/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-array-nanmeanwd/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-array-nanmeanwd/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-array-nanmeanwd/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-array-nanmeanwd/main/LICENSE

[arithmetic-mean]: https://en.wikipedia.org/wiki/Arithmetic_mean

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

</section>

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