time-to-botec/squiggle/node_modules/@stdlib/stats/iter/mrange/README.md

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# itermrange

> Create an [iterator][mdn-iterator-protocol] which iteratively computes a moving [range][range].

<section class="intro">

The [**range**][range] is defined as the difference between the maximum and minimum values.

</section>

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<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var itermrange = require( '@stdlib/stats/iter/mrange' );
```

#### itermrange( iterator, W )

Returns an [iterator][mdn-iterator-protocol] which iteratively computes a moving [range][range]. The `W` parameter defines the number of iterated values over which to compute the moving [range][range].

```javascript
var array2iterator = require( '@stdlib/array/to-iterator' );

var arr = array2iterator( [ 2.0, 1.0, 3.0, -7.0, -5.0 ] );
var it = itermrange( arr, 3 );

// Fill the window...
var v = it.next().value; // [2.0]
// returns 0.0

v = it.next().value; // [2.0, 1.0]
// returns 1.0

v = it.next().value; // [2.0, 1.0, 3.0]
// returns 2.0

// Window begins sliding...
v = it.next().value; // [1.0, 3.0, -7.0]
// returns 10.0

v = it.next().value; // [3.0, -7.0, -5.0]
// returns 10.0
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   If an iterated value is non-numeric (including `NaN`), the function returns `NaN` for **at least** `W-1` future invocations. If non-numeric iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles non-numeric values accordingly.
-   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 previously iterated values.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var runif = require( '@stdlib/random/iter/uniform' );
var itermrange = require( '@stdlib/stats/iter/mrange' );

// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( -10.0, 10.0, {
    'seed': 1234,
    'iter': 100
});

// Create an iterator for iteratively computing a moving range:
var it = itermrange( rand, 3 );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( typeof v.value === 'number' ) {
        console.log( 'range: %d', v.value );
    }
    if ( v.done ) {
        break;
    }
}
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

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<section class="links">

[range]: https://en.wikipedia.org/wiki/Range_%28statistics%29

[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol

</section>

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