@stdlib/iter-slice
v0.2.2
Published
Create an iterator which returns a subsequence of iterated values from a provided iterator.
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iterSlice
Create an iterator which returns a subsequence of iterated values from a provided iterator.
Installation
npm install @stdlib/iter-slice
Usage
var iterSlice = require( '@stdlib/iter-slice' );
iterSlice( iterator[, begin[, end]] )
Returns an iterator which returns a subsequence of iterated values from a provided iterator.
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterSlice( array2iterator( [ 1, 2, 3, 4 ] ) );
// returns <Object>
var v = it.next().value;
// returns 1
v = it.next().value;
// returns 2
v = it.next().value;
// returns 3
// ...
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 adone
property having aboolean
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.
By default, the returned iterator returns a provided iterator's first iterated value through an iterator's last iterated value. To specify an alternative start iteration index (zero-based and inclusive), provide a begin
argument.
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterSlice( array2iterator( [ 1, 2, 3, 4 ] ), 2 );
// returns <Object>
var v = it.next().value;
// returns 3
v = it.next().value;
// returns 4
var bool = it.next().done;
// returns true
By default, the returned iterator continues iterating until it consumes all of a provided iterator's iterated values. To specify an end iteration index (zero-based and non-inclusive), provide an end
argument.
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterSlice( array2iterator( [ 1, 2, 3, 4 ] ), 1, 3 );
// returns <Object>
var v = it.next().value;
// returns 2
v = it.next().value;
// returns 3
var bool = it.next().done;
// returns true
If begin
is greater than or equal to end
, the returned iterator does not return any iterated values.
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterSlice( array2iterator( [ 1, 2, 3, 4 ] ), 3, 1 );
// returns <Object>
var bool = it.next().done;
// returns true
Notes
- If an environment supports
Symbol.iterator
and a provided iterator is iterable, the returned iterator is iterable.
Examples
var randu = require( '@stdlib/random-iter-randu' );
var iterSlice = require( '@stdlib/iter-slice' );
// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
'seed': 1234
});
// Create an iterator which returns a subsequence of 10 generated numbers:
var it = iterSlice( rand, 10, 20 );
// Perform manual iteration...
var r;
while ( true ) {
r = it.next();
if ( r.done ) {
break;
}
console.log( r.value );
}
See Also
@stdlib/iter-first
: return the first iterated value.@stdlib/iter-head
: create an iterator which returns the firstn
values of a provided iterator.
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.