npm package: @stdlib/stats-incr-nanmsum
Description: Compute a moving sum incrementally, ignoring NaN values.
Author: The Stdlib Authors
Latest version: 0.1.1

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# incrnanmsum

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

> Compute a moving sum incrementally, ignoring `NaN` values.

<section class="intro">

For a window of size `W`, the moving sum is defined as

<!-- <equation class="equation" label="eq:moving_sum" align="center" raw="s = \sum_{i=0}^{W-1} x_i" alt="Equation for the moving sum."> -->

<div class="equation" align="center" data-raw-text="s = \sum_{i=0}^{W-1} x_i" data-equation="eq:moving_sum">
    <img src="./docs/img/equation_moving_sum.svg" alt="Equation for the moving sum.">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/stats-incr-nanmsum
```

</section>

<section class="usage">

## Usage

```javascript
var incrnanmsum = require( '@stdlib/stats-incr-nanmsum' );
```

#### incrnanmsum( window )

Returns an accumulator function which incrementally computes a moving sum. The `window` parameter defines the number of values over which to compute the moving sum.

```javascript
var accumulator = incrnanmsum( 3 );
```

#### accumulator( \[x] )

If provided an input value `x`, the accumulator function returns an updated sum. If not provided an input value `x`, the accumulator function returns the current sum.

```javascript
var accumulator = incrnanmsum( 3 );

var sum = accumulator();
// returns null

sum = accumulator( 2.0 );
// returns 2.0

sum = accumulator( NaN );
// returns 2.0

sum = accumulator( -5.0 );
// returns -3.0

sum = accumulator( 3.0 );
// returns 0.0

sum = accumulator( 5.0 );
// returns 3.0

sum = accumulator();
// returns 3.0
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   Input values are **not** type checked. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
-   As `W` values are needed to fill the window buffer, the first `W-1` returned values are calculated from smaller sample sizes. Until the window is full, each returned value is calculated from all provided values.

</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 incrnanmsum = require( '@stdlib/stats-incr-nanmsum' );

// Initialize an accumulator:
var accumulator = incrnanmsum( 5 );

// For each simulated datum, update the moving sum...
var i;
for ( i = 0; i < 100; i++ ) {
    accumulator( ( bernoulli( 0.8 ) < 1 ) ? NaN : uniform( -50.0, 50.0 ) );
}
console.log( accumulator() );
```

</section>

<!-- /.examples -->

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<section class="related">

</section>

<!-- /.related -->

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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].

</section>

<!-- /.stdlib -->

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