nanmidrange

Calculate the mid-range of a strided array, ignoring NaN values.

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

Installation

npm install @stdlib/stats-strided-nanmidrange

Usage

var nanmidrange = require( '@stdlib/stats-strided-nanmidrange' );

nanmidrange( N, x, strideX )

Computes the mid-range of a strided array, ignoring NaN values.

var x = [ 1.0, -2.0, NaN, 2.0 ];
var N = x.length;

var v = nanmidrange( N, x, 1 );
// returns 0.0

The function has the following parameters:

• N: number of indexed elements.
• x: input Array or typed array.
• strideX: stride length for x.

The N and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the mid-range of every other element in x,

var x = [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0, NaN, NaN ];

var v = nanmidrange( 5, x, 2 );
// returns 1.0

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

var Float64Array = require( '@stdlib/array-float64' );

var x0 = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, NaN, NaN, 4.0 ] );
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var v = nanmidrange( 4, x1, 2 );
// returns 1.0

nanmidrange.ndarray( N, x, strideX, offsetX )

Computes the mid-range of a strided array, ignoring NaN values and using alternative indexing semantics.

var x = [ 1.0, -2.0, NaN, 2.0 ];
var N = x.length;

var v = nanmidrange.ndarray( N, x, 1, 0 );
// returns 0.0

The function has the following additional parameters:

• offsetX: starting index for x.

While typed array views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to calculate the mid-range for every other element in the strided array starting from the second element

var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, NaN, NaN, 2.0, 3.0, 4.0 ];

var v = nanmidrange.ndarray( 5, x, 2, 1 );
// returns 1.0

Notes

• If N <= 0, both functions return NaN.
• Both functions support array-like objects having getter and setter accessors for array element access (e.g., @stdlib/array-base/accessor).
• Depending on the environment, the typed versions (dnanmidrange, snanmidrange, etc.) are likely to be significantly more performant.

Examples

var uniform = require( '@stdlib/random-base-uniform' );
var filledarrayBy = require( '@stdlib/array-filled-by' );
var bernoulli = require( '@stdlib/random-base-bernoulli' );
var nanmidrange = require( '@stdlib/stats-strided-nanmidrange' );

function rand() {
    if ( bernoulli( 0.8 ) < 1 ) {
        return NaN;
    }
    return uniform( -50.0, 50.0 );
}

var x = filledarrayBy( 10, 'float64', rand );
console.log( x );

var v = nanmidrange( x.length, x, 1 );
console.log( v );

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.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.