@stdlib/iter-strided NPM

iterStrided

Create an iterator which steps by a specified amount.

Installation

npm install @stdlib/iter-strided

Usage

var iterStrided = require( '@stdlib/iter-strided' );

iterStrided( iterator, stride[, offset[, eager]] )

Returns an iterator which steps by a specified amount.

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

var arr = array2iterator( [ 1, 2, 3, 4, 5, 6, 7, 8 ] );
var it = iterStrided( arr, 2 );
// returns <Object>

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

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

r = it.next().value;
// returns 5

// ...

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.

To skip the first N values of a provided iterator, provide an offset argument.

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

var arr = array2iterator( [ 1, 2, 3, 4, 5, 6, 7, 8 ] );
var it = iterStrided( arr, 2, 1 );
// returns <Object>

var r = it.next().value;
// returns 2

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

r = it.next().value;
// returns 6

// ...

By default, the returned iterator defers consuming the first N input iterator values until the first value of the returned iterator is consumed. To eagerly advance the input iterator, set the eager argument to true.

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

var arr = array2iterator( [ 1, 2, 3, 4, 5, 6, 7, 8 ] );
var it = iterStrided( arr, 1, 4, true );
// returns <Object>

var r = it.next().value;
// returns 5

r = it.next().value;
// returns 6

r = it.next().value;
// returns 7

// ...

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 iterStrided = require( '@stdlib/iter-strided' );

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

// Create an iterator which returns every other random number:
var it = iterStrided( rand, 2 );

// 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.