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iterFill

Create an iterator which replaces all values from a provided iterator from a start index to an end index with a static value.

Installation

npm install @stdlib/iter-fill

Alternatively,

To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
If you are using Deno, visit the deno branch (see README for usage intructions).
For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var iterFill = require( '@stdlib/iter-fill' );

iterFill( iterator, value[, begin[, end]] )

Returns an iterator which replaces all values from a provided iterator from a begin index to an end index with a static value.

var array2iterator = require( '@stdlib/array-to-iterator' );

var it = iterFill( array2iterator( [ 1, 2, 3, 4 ] ), 3.14 );
// returns <Object>

var v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

// ...

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.

By default, the returned iterator replaces/fills a provided iterator's first iterated value through an iterator's last iterated value. To specify an alternative start iteration index at which to begin filling (zero-based and inclusive), provide a begin argument.

var array2iterator = require( '@stdlib/array-to-iterator' );

var it = iterFill( array2iterator( [ 1, 2, 3, 4 ] ), 3.14, 2 );
// returns <Object>

var v = it.next().value;
// returns 1

v = it.next().value;
// returns 2

v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

var bool = it.next().done;
// returns true

By default, the returned iterator continues filling until it replaces all of a provided iterator's iterated values. To specify an end iteration index at which to stop filling (zero-based and non-inclusive), provide an end argument.

var array2iterator = require( '@stdlib/array-to-iterator' );

var it = iterFill( array2iterator( [ 1, 2, 3, 4 ] ), 3.14, 1, 3 );
// returns <Object>

var v = it.next().value;
// returns 1

v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 4

var bool = it.next().done;
// returns true

If begin is greater than or equal to end, the returned iterator does not replace any iterated values.

var array2iterator = require( '@stdlib/array-to-iterator' );

var it = iterFill( array2iterator( [ 1, 2, 3, 4 ] ), 3.14, 3, 1 );
// returns <Object>

var v = it.next().value;
// returns 1

v = it.next().value;
// returns 2

v = it.next().value;
// returns 3

v = it.next().value;
// returns 4

var bool = it.next().done;
// returns true

Notes

If end exceeds the length of the provided iterator, the returned iterator replaces the subsequence of iterated values starting from begin until the last iterated value of the provided iterator.
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 iterFill = require( '@stdlib/iter-fill' );

// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
    'seed': 1234,
    'iter': 100
});

// Create an iterator which replaces a subsequence of 10 generated numbers:
var it = iterFill( rand, 3.14, 10, 20 );

// Perform manual iteration...
var r;
while ( true ) {
    r = it.next();
    if ( r.done ) {
        break;
    }
    console.log( r.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-js/iter-fill