Compute a moving arithmetic mean incrementally.
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> Compute a moving [arithmetic mean][arithmetic-mean] incrementally.
For a window of size W, the [arithmetic mean][arithmetic-mean] is defined as
``bash`
npm install @stdlib/stats-incr-mmean
`javascript`
var incrmmean = require( '@stdlib/stats-incr-mmean' );
#### incrmmean( window )
Returns an accumulator function which incrementally computes a moving [arithmetic mean][arithmetic-mean]. The window parameter defines the number of values over which to compute the moving mean.
`javascript`
var accumulator = incrmmean( 3 );
#### accumulator( \[x] )
If provided an input value x, the accumulator function returns an updated mean. If not provided an input value x, the accumulator function returns the current mean.
`javascript
var accumulator = incrmmean( 3 );
var mu = accumulator();
// returns null
// Fill the window...
mu = accumulator( 2.0 ); // [2.0]
// returns 2.0
mu = accumulator( 1.0 ); // [2.0, 1.0]
// returns 1.5
mu = accumulator( 3.0 ); // [2.0, 1.0, 3.0]
// returns 2.0
// Window begins sliding...
mu = accumulator( -7.0 ); // [1.0, 3.0, -7.0]
// returns -1.0
mu = accumulator( -5.0 ); // [3.0, -7.0, -5.0]
// returns -3.0
mu = accumulator();
// returns -3.0
`
- Input values are not type checked. If provided NaN or a value which, when used in computations, results in NaN, the accumulated value is NaN for at least W-1 future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly before passing the value to the accumulator function.W
- As 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.
`javascript
var randu = require( '@stdlib/random-base-randu' );
var incrmmean = require( '@stdlib/stats-incr-mmean' );
var accumulator;
var v;
var i;
// Initialize an accumulator:
accumulator = incrmmean( 5 );
// For each simulated datum, update the moving mean...
for ( i = 0; i < 100; i++ ) {
v = randu() * 100.0;
accumulator( v );
}
console.log( accumulator() );
`
*
- [@stdlib/stats-incr/mean][@stdlib/stats/incr/mean]: compute an arithmetic mean incrementally.
- [@stdlib/stats-incr/msum][@stdlib/stats/incr/msum]: compute a moving sum incrementally.
- [@stdlib/stats-incr/mstdev][@stdlib/stats/incr/mstdev]: compute a moving corrected sample standard deviation incrementally.
- [@stdlib/stats-incr/msummary][@stdlib/stats/incr/msummary]: compute a moving statistical summary incrementally.
- [@stdlib/stats-incr/mvariance][@stdlib/stats/incr/mvariance]: compute a moving unbiased sample variance incrementally.
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[stdlib]: https://github.com/stdlib-js/stdlib
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[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-incr-mmean/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-incr-mmean/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-incr-mmean/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-incr-mmean/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-incr-mmean/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-incr-mmean/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-incr-mmean/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-incr-mmean/main/LICENSE
[arithmetic-mean]: https://en.wikipedia.org/wiki/Arithmetic_mean
[@stdlib/stats/incr/mean]: https://www.npmjs.com/package/@stdlib/stats-incr-mean
[@stdlib/stats/incr/msum]: https://www.npmjs.com/package/@stdlib/stats-incr-msum
[@stdlib/stats/incr/mstdev]: https://www.npmjs.com/package/@stdlib/stats-incr-mstdev
[@stdlib/stats/incr/msummary]: https://www.npmjs.com/package/@stdlib/stats-incr-msummary
[@stdlib/stats/incr/mvariance]: https://www.npmjs.com/package/@stdlib/stats-incr-mvariance