stdlib-js
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About stdlib...
</summary>
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ind
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Return an index given an index mode.
bash
npm install @stdlib/ndarray-base-ind
javascript
var ind = require( '@stdlib/ndarray-base-ind' );
#### ind( idx, max, mode )
Returns an index given an index mode.
javascript
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.
javascript
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.
[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 to 0 (minimum index) and set an index greater than max to max.
javascript
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 );
}
