README

ind

Return an index given an index mode.

Installation

npm install @stdlib/ndarray-base-ind

Usage

var ind = require( '@stdlib/ndarray-base-ind' );

ind( idx, max, mode )

Returns an index given an index mode.

var idx = ind( 2, 9, 'throw' );
// returns 2

idx = ind( -1, 9, 'throw' );
// throws <RangeError>

idx = ind( 10, 9, 'throw' );
// throws <RangeError>

The function supports the following modes:

throw: specifies that the function should throw an error when an index is outside the interval [0,max].
wrap: specifies that the function should wrap around an index using modulo arithmetic.
clamp: specifies that the function should set an index less than 0 to 0 (minimum index) and set an index greater than max to max.

var idx = ind( 2, 9, 'wrap' );
// returns 2

idx = ind( 10, 9, 'wrap' );
// returns 0

idx = ind( -1, 9, 'wrap' );
// returns 9

idx = ind( 2, 9, 'clamp' );
// returns 2

idx = ind( 10, 9, 'clamp' );
// returns 9

idx = ind( -1, 9, 'clamp' );
// returns 0

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var ind = require( '@stdlib/ndarray-base-ind' );

var modes;
var mode;
var idx;
var out;
var i;

modes = [ 'clamp', 'wrap' ];

for ( i = 0; i < 100; i++ ) {
    idx = discreteUniform( -20, 20 );
    mode = modes[ discreteUniform( 0, modes.length-1 ) ];
    out = ind( idx, 9, mode );
    console.log( '%d => %s(%d,%d) => %d', idx, mode, 0, 9, out );
}

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.

@stdlib/ndarray-base-ind

Usage no npm install needed!