@stdlib/ndarray-base-ind
v0.2.2
Published
Return an index given an index mode.
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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>
// Wrapping indices around using modulo arithmetic:
idx = ind( 2, 9, 'wrap' );
// returns 2
idx = ind( 10, 9, 'wrap' );
// returns 0
idx = ind( -1, 9, 'wrap' );
// returns 9
// Clamping indices to first and last indices:
idx = ind( 2, 9, 'clamp' );
// returns 2
idx = ind( 10, 9, 'clamp' );
// returns 9
idx = ind( -1, 9, 'clamp' );
// returns 0
// Normalizing negative indices:
idx = ind( 2, 9, 'normalize' );
// returns 2
idx = ind( -4, 9, 'normalize' );
// returns 6
ind.factory( mode )
Returns a function for returning an index according to a provided index mode
.
var fcn = ind.factory( 'clamp' );
var idx = fcn( 2, 9 );
// returns 2
idx = fcn( 10, 9 );
// returns 9
idx = fcn( -1, 9 );
// returns 0
The function returns a function accepts the following arguments:
- index: input index.
- max: maximum index value.
Notes
Both functions support the following modes:
- throw: specifies that the function should throw an error when an index is outside the interval
[0, max]
. - normalize: specifies that the function should normalize negative indices and throw an error when an index is outside the interval
[-max-1, 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
to0
(minimum index) and set an index greater thanmax
tomax
.
- throw: specifies that the function should throw an error when an index is outside the interval
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.
Copyright
Copyright © 2016-2024. The Stdlib Authors.