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    @stdlib/stats-base-range
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    0.0.7 • Public • Published

    range

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    Calculate the range of a strided array.

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

    Installation

    npm install @stdlib/stats-base-range

    Usage

    var range = require( '@stdlib/stats-base-range' );

    range( N, x, stride )

    Computes the range of a strided array x.

    var x = [ 1.0, -2.0, 2.0 ];
    var N = x.length;
    
    var v = range( N, x, 1 );
    // returns 4.0

    The function has the following parameters:

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

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

    var floor = require( '@stdlib/math-base-special-floor' );
    
    var x = [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ];
    var N = floor( x.length / 2 );
    
    var v = range( N, x, 2 );
    // returns 6.0

    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' );
    
    var x0 = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
    var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
    
    var N = floor( x0.length / 2 );
    
    var v = range( N, x1, 2 );
    // returns 6.0

    range.ndarray( N, x, stride, offset )

    Computes the range of a strided array using alternative indexing semantics.

    var x = [ 1.0, -2.0, 2.0 ];
    var N = x.length;
    
    var v = range.ndarray( N, x, 1, 0 );
    // returns 4.0

    The function has the following additional parameters:

    • offset: 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 range for every other value in x starting from the second value

    var floor = require( '@stdlib/math-base-special-floor' );
    
    var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ];
    var N = floor( x.length / 2 );
    
    var v = range.ndarray( N, x, 2, 1 );
    // returns 6.0

    Notes

    • If N <= 0, both functions return NaN.
    • Depending on the environment, the typed versions (drange, srange, etc.) are likely to be significantly more performant.

    Examples

    var randu = require( '@stdlib/random-base-randu' );
    var round = require( '@stdlib/math-base-special-round' );
    var Float64Array = require( '@stdlib/array-float64' );
    var range = require( '@stdlib/stats-base-range' );
    
    var x;
    var i;
    
    x = new Float64Array( 10 );
    for ( i = 0; i < x.length; i++ ) {
        x[ i ] = round( (randu()*100.0) - 50.0 );
    }
    console.log( x );
    
    var v = range( x.length, x, 1 );
    console.log( v );

    See Also


    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.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2022. The Stdlib Authors.

    Install

    npm i @stdlib/stats-base-range

    Homepage

    stdlib.io

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    232

    Version

    0.0.7

    License

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    Unpacked Size

    50.1 kB

    Total Files

    11

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