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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

iterReplicateBy

NPM version Build Status Coverage Status

Create an iterator which replicates each iterated value according to a provided function.

Usage

import iterReplicateBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/iter-replicate-by@esm/index.mjs';

iterReplicateBy( iterator, fcn[, thisArg] )

Returns an iterator which replicates each iterated value according to a provided function.

import array2iterator from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-to-iterator@esm/index.mjs';

function fcn( v, i ) {
    return i + 1;
}

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

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

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

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

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

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

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

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

// ...

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.

The callback function is provided three arguments:

  • value: iterated value
  • index: source iteration index (zero-based)
  • n: iteration index (zero-based)

To set the callback execution context, provide a thisArg.

import array2iterator from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-to-iterator@esm/index.mjs';

function fcn( v, i ) {
    this.count += 1;
    return i + 1;
}

var ctx = {
    'count': 0
};

var it = iterReplicateBy( array2iterator( [ 1, 2, 3, 4 ] ), fcn, ctx );
// returns <Object>

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

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

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

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

var count = ctx.count;
// returns 3

Notes

  • A callback function is invoked once per iterated value of the provided iterator.
  • A callback function must return an integer value. If the return value is less than or equal to 0, the returned iterator skips an iterated value and invokes the callback for the next iterated value of the provided iterator.
  • If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">

import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-iter-randu@esm/index.mjs';
import discreteUniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-discrete-uniform@esm/index.mjs';
import iterReplicateBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/iter-replicate-by@esm/index.mjs';

// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
    'seed': 1234,
    'iter': 10
});

// Create an iterator which replicates each generated number a random number of times:
var it = iterReplicateBy( rand, discreteUniform.factory( 1, 10 ) );

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

</script>
</body>
</html>

See Also

  • @stdlib/iter-replicate: create an iterator which replicates each iterated value a specified number of times.

Notice

This package is part of stdlib, a standard library 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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.