incrmrange

Compute a moving range incrementally.

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

Usage

var incrmrange = require( '@stdlib/stats/incr/mrange' );

incrmrange( window )

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

var accumulator = incrmrange( 3 );

accumulator( [x] )

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

var accumulator = incrmrange( 3 );

var r = accumulator();
// returns null

// Fill the window...
r = accumulator( 2.0 ); // [2.0]
// returns 0.0

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

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

// Window begins sliding...
r = accumulator( -7.0 ); // [1.0, 3.0, -7.0]
// returns 10.0

r = accumulator( -5.0 ); // [3.0, -7.0, -5.0]
// returns 10.0

r = accumulator();
// returns 10.0

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 incrmrange = require( '@stdlib/stats/incr/mrange' );

var accumulator;
var v;
var i;

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

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