# itermmidrange

Create an iterator which iteratively computes a moving mid-range.

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.

## Usage

``````var itermmidrange = require( '@stdlib/stats/iter/mmidrange' );
``````

#### itermmidrange( iterator, W )

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

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

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

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

v = it.next().value; // [2.0, 1.0]
// returns 1.5

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 -2.0

v = it.next().value; // [3.0, -7.0, -5.0]
// returns -2.0
``````

## 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` 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.

## Examples

``````var runif = require( '@stdlib/random/iter/uniform' );
var itermmidrange = require( '@stdlib/stats/iter/mmidrange' );

// 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 mid-range:
var it = itermmidrange( rand, 3 );

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