time-to-botec/squiggle/node_modules/@stdlib/stats/incr/msummary/README.md

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# incrmsummary

> Compute a moving statistical summary incrementally.

<section class="usage">

## Usage

```javascript
var incrmsummary = require( '@stdlib/stats/incr/msummary' );
```

#### incrmsummary( window )

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

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

#### accumulator( \[x] )

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

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

var summary = accumulator();
// returns {}

// Fill the window...
summary = accumulator( 2.0 ); // [2.0]
/* returns
    {
        'window': 3,
        'sum': 2.0,
        'mean': 2.0,
        'variance': 0.0,
        'stdev': 0.0,
        'min': 2.0,
        'max': 2.0,
        'range': 0.0,
        'midrange': 2.0
    }
*/

summary = accumulator( 1.0 ); // [2.0, 1.0]
/* returns
    {
        'window': 3,
        'sum': 3.0,
        'mean': 1.5,
        'variance': 0.5,
        'stdev': 0.7071067811865476,
        'min': 1.0,
        'max': 2.0,
        'range': 1.0,
        'midrange': 1.5
    }
*/

summary = accumulator( -3.0 ); // [2.0, 1.0, -3.0]
/* returns
    {
        'window': 3,
        'sum': 0.0,
        'mean': 0.0,
        'variance': 7.0,
        'stdev': 2.6457513110645907,
        'min': -3.0,
        'max': 2.0,
        'range': 5.0,
        'midrange': -0.5
    }
*/

// Window begins sliding...
summary = accumulator( -7.0 ); // [1.0, -3.0, -7.0]
// returns {...}

summary = accumulator( -5.0 ); // [-3.0, -7.0, -5.0]
// returns {...}

summary = accumulator();
// returns {...}
```

</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 summaries are calculated from smaller sample sizes. Until the window is full, each returned summary is calculated from all provided values.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random/base/randu' );
var incrmsummary = require( '@stdlib/stats/incr/msummary' );

var accumulator;
var v;
var i;

// Initialize an accumulator:
accumulator = incrmsummary( 5 );

// For each simulated datum, update the moving summary...
for ( i = 0; i < 100; i++ ) {
    v = randu() * 100.0;
    accumulator( v );
}
console.log( accumulator() );
```

</section>

<!-- /.examples -->

<section class="links">

</section>

<!-- /.links -->