About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

nanrangeBy

Calculate the range of a strided array via a callback function, ignoring NaN values.

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

Installation

npm install @stdlib/stats-base-nanrange-by

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var nanrangeBy = require( '@stdlib/stats-base-nanrange-by' );

nanrangeBy( N, x, stride, clbk[, thisArg] )

Calculates the range of strided array x via a callback function, ignoring NaN values.

function accessor( v ) {
    return v * 2.0;
}

var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, NaN, 0.0, -1.0, -3.0, NaN ];

var v = nanrangeBy( x.length, x, 1, accessor );
// returns 18.0

The function has the following parameters:

• N: number of indexed elements.
• x: input Array, typed array, or an array-like object (excluding strings and functions).
• stride: index increment.
• clbk: callback function.
• thisArg: execution context (optional).

The invoked callback is provided four arguments:

• value: array element.
• aidx: array index.
• sidx: strided index (offset + aidx*stride).
• array: input array/collection.

To set the callback execution context, provide a thisArg.

function accessor( v ) {
    this.count += 1;
    return v * 2.0;
}

var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, NaN, 0.0, -1.0, -3.0, NaN ];

var context = {
    'count': 0
};

var v = nanrangeBy( x.length, x, 1, accessor, context );
// returns 18.0

var cnt = context.count;
// returns 10

The N and stride parameters determine which elements in x are accessed at runtime. For example, to access every other element

var floor = require( '@stdlib/math-base-special-floor' );

function accessor( v ) {
    return v * 2.0;
}

var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0, NaN, NaN ];
var N = floor( x.length / 2 );

var v = nanrangeBy( N, x, 2, accessor );
// returns 12.0

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

var Float64Array = require( '@stdlib/array-float64' );
var floor = require( '@stdlib/math-base-special-floor' );

function accessor( v ) {
    return v * 2.0;
}

// Initial array...
var x0 = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );

// Create an offset view...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var N = floor( x0.length/2 );

// Access every other element...
var v = nanrangeBy( N, x1, 2, accessor );
// returns 8.0

nanrangeBy.ndarray( N, x, stride, offset, clbk[, thisArg] )

Calculates the range of strided array x via a callback function, ignoring NaN values and using alternative indexing semantics.

function accessor( v ) {
    return v * 2.0;
}

var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, NaN, 0.0, -1.0, -3.0, NaN ];

var v = nanrangeBy.ndarray( x.length, x, 1, 0, accessor );
// returns 18.0

The function has the following additional parameters:

• offset: starting index.

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 access only the last three elements of x

function accessor( v ) {
    return v * 2.0;
}

var x = [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ];

var v = nanrangeBy.ndarray( 3, x, 1, x.length-3, accessor );
// returns 22.0

Notes

• If N <= 0, both functions return NaN.
• A provided callback function should return a numeric value.
• If a provided callback function returns NaN, the value is ignored.
• If a provided callback function does not return any value (or equivalently, explicitly returns undefined), the value is ignored.
• When possible, prefer using dnanrange, snanrange, and/or nanrange, as, depending on the environment, these interfaces are likely to be significantly more performant.

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var randu = require( '@stdlib/random-base-randu' );
var filledarrayBy = require( '@stdlib/array-filled-by' );
var nanrangeBy = require( '@stdlib/stats-base-nanrange-by' );

function fill() {
    if ( randu() < 0.2 ) {
        return NaN;
    }
    return discreteUniform( -50, 50 );
}

function accessor( v ) {
    return v * 2.0;
}

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

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

---

See Also

• @stdlib/stats-base/dnanrange: calculate the range of a double-precision floating-point strided array, ignoring NaN values.
• @stdlib/stats-base/nanmax-by: calculate the maximum value of a strided array via a callback function, ignoring NaN values.
• @stdlib/stats-base/nanmin-by: calculate the minimum value of a strided array via a callback function, ignoring NaN values.
• @stdlib/stats-base/nanrange: calculate the range of a strided array, ignoring NaN values.
• @stdlib/stats-base/range-by: calculate the range of a strided array via a callback function.
• @stdlib/stats-base/snanrange: calculate the range of a single-precision floating-point strided array, ignoring NaN values.

---

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 © 2016-2024. The Stdlib Authors.