# @stdlib/stats-incr-mmidrange

0.2.1 • Public • Published

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# incrmmidrange

Compute a moving mid-range incrementally.

The mid-range, or mid-extreme, is the arithmetic mean of maximum and minimum values. Accordingly, the mid-range is the midpoint of the range and a measure of central tendency.

## Installation

`npm install @stdlib/stats-incr-mmidrange`

## Usage

`var incrmmidrange = require( '@stdlib/stats-incr-mmidrange' );`

#### incrmmidrange( window )

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

`var accumulator = incrmmidrange( 3 );`

#### accumulator( [x] )

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

```var accumulator = incrmmidrange( 3 );

var mr = accumulator();
// returns null

// Fill the window...
mr = accumulator( 2.0 ); // [2.0]
// returns 2.0

mr = accumulator( 1.0 ); // [2.0, 1.0]
// returns 1.5

mr = accumulator( 3.0 ); // [2.0, 1.0, 3.0]
// returns 2.0

// Window begins sliding...
mr = accumulator( -7.0 ); // [1.0, 3.0, -7.0]
// returns -2.0

mr = accumulator( -5.0 ); // [3.0, -7.0, -5.0]
// returns -2.0

mr = accumulator();
// returns -2.0```

## Notes

• Input values are not type checked. If provided `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.
• 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.

## Examples

```var randu = require( '@stdlib/random-base-randu' );
var incrmmidrange = require( '@stdlib/stats-incr-mmidrange' );

var accumulator;
var v;
var i;

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

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

## Notice

This package is part of 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, see the main project repository.

## Package Sidebar

### Install

`npm i @stdlib/stats-incr-mmidrange`

### Repository

github.com/stdlib-js/stats-incr-mmidrange

stdlib.io

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0.2.1

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