@stdlib/ndarray-iter-indices NPM

nditerIndices

Create an iterator which returns indices for use indexing into an ndarray having a specified shape.

Installation

npm install @stdlib/ndarray-iter-indices

Usage

var nditerIndices = require( '@stdlib/ndarray-iter-indices' );

nditerIndices( shape[, options] )

Returns an iterator which returns indices for use indexing into an ndarray having a specified shape.

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

var x = array( [ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 5, 6 ], [ 7, 8 ] ] ] );
// returns <ndarray>

var iter = nditerIndices( x.shape );

var v = iter.next().value;
// returns [ 0, 0, 0 ]

v = iter.next().value;
// returns [ 0, 0, 1 ]

v = iter.next().value;
// returns [ 0, 1, 0 ]

// ...

The function accepts the following options:

order: index iteration order. By default, the returned iterator iterates over the last dimensions first, thus corresponding to iteration over contiguous data stored in row-major order. Must be either 'row-major' or 'column-major'.

By default, the iterator returns indices such that the last dimensions are iterated over first. To return indices according to a specified order, set the order option.

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

var x = array( [ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 5, 6 ], [ 7, 8 ] ] ], {
    'order': 'row-major'
});
// returns <ndarray>

var iter = nditerIndices( x.shape, {
    'order': 'column-major'
});

var v = iter.next().value;
// returns [ 0, 0, 0 ]

v = iter.next().value;
// returns [ 1, 0, 0 ]

v = iter.next().value;
// returns [ 0, 1, 0 ]

// ...

The returned iterator protocol-compliant object has the following properties:

next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

Notes

If an environment supports Symbol.iterator, the returned iterator is iterable.

Examples

var array = require( '@stdlib/ndarray-array' );
var zeroTo = require( '@stdlib/array-base-zero-to' );
var nditerIndices = require( '@stdlib/ndarray-iter-indices' );

// Define an input array:
var x = array( zeroTo( 27 ), {
    'shape': [ 3, 3, 3 ]
});

// Create an iterator for generating indices:
var it = nditerIndices( x.shape );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( v.done ) {
        break;
    }
    console.log( x.get.apply( x, v.value ) );
}

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-iter-indices v0.2.1