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https://github.com/stdlib-js/iter-pipeline

Create an iterator pipeline.
https://github.com/stdlib-js/iter-pipeline

flow funseq iter iterate iterator javascript node node-js nodejs pipe pipeline stdlib stream util utilities utility utils

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Create an iterator pipeline.

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README 

        



  

    About stdlib...

  

  
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# iterPipeline



[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] 



> Create an [iterator][mdn-iterator-protocol] pipeline.



## Installation



```bash

npm install @stdlib/iter-pipeline

```



Alternatively,



-   To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).

-   If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).

-   For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).



The [branches.md][branches-url] 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



```javascript

var iterPipeline = require( '@stdlib/iter-pipeline' );

```



#### iterPipeline( iterFcn0\[, ...iterFcn] )



Returns an [iterator][mdn-iterator-protocol] pipeline.



```javascript

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

var iterThunk = require( '@stdlib/iter-pipeline-thunk' );

var iterHead = require( '@stdlib/iter-head' );

var iterSome = require( '@stdlib/iter-some' );



// Convert iterator functions to unary functions which accept an iterator:

var it1 = iterThunk( iterHead, 5 );

var it2 = iterThunk( iterSome, 3 );



// Create an iterator pipeline:

var p = iterPipeline( it1, it2 );



// Create a source iterator:

var arr = array2iterator( [ 0, 0, 1, 1, 1, 0, 0, 0, 1, 1 ] );



// Provide the source iterator to our iterator pipeline:

var bool = p( arr );

// returns true



// Create a new source iterator:

arr = array2iterator( [ 0, 0, 1, 0, 1, 0, 0, 0, 1, 1 ] );



// Run the pipeline for the new source iterator:

bool = p( arr );

// returns false

```



The function accepts [iterator][mdn-iterator-protocol] functions provided as separate arguments **or** as a single argument consisting of an array of [iterator][mdn-iterator-protocol] functions.



```javascript

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

var iterThunk = require( '@stdlib/iter-pipeline-thunk' );

var iterHead = require( '@stdlib/iter-head' );

var iterSome = require( '@stdlib/iter-some' );



var it1 = iterThunk( iterHead, 5 );

var it2 = iterThunk( iterSome, 3 );



var p = iterPipeline( [ it1, it2 ] );



var arr = array2iterator( [ 0, 0, 1, 1, 1, 0, 0, 0, 1, 1 ] );

var bool = p( arr );

// returns true



arr = array2iterator( [ 0, 0, 1, 0, 1, 0, 0, 0, 1, 1 ] );

bool = p( arr );

// returns false

```



## Notes



-   Within the context of an [iterator][mdn-iterator-protocol] pipeline (as defined by this function), an [iterator][mdn-iterator-protocol] function is defined as a **unary** function which accepts an [iterator][mdn-iterator-protocol] as its **only** argument.

-   Each [iterator][mdn-iterator-protocol] function, except the last [iterator][mdn-iterator-protocol] function, within an [iterator][mdn-iterator-protocol] pipeline must return an [iterator][mdn-iterator-protocol].

-   Starting from the left, each returned [iterator][mdn-iterator-protocol] is passed to the next [iterator][mdn-iterator-protocol] function.

-   The result of the last [iterator][mdn-iterator-protocol] function is the result of the pipeline.



## Examples



```javascript

var randu = require( '@stdlib/random-iter-randu' );

var iterHead = require( '@stdlib/iter-head' );

var iterMap = require( '@stdlib/iter-map' );

var iterSome = require( '@stdlib/iter-some' );

var iterThunk = require( '@stdlib/iter-pipeline-thunk' );

var iterPipeline = require( '@stdlib/iter-pipeline' );



function threshold( r ) {

    return ( r > 0.95 );

}



// Create a pipeline which tests whether at least 5% of values exceed a threshold:

var p = iterPipeline(

    // Apply a threshold to iterated values:

    iterThunk( iterMap, threshold ),



    // Limit the sequence to 100 values:

    iterThunk( iterHead, 100 ),



    // Test whether at least 5 values exceed the threshold:

    iterThunk( iterSome, 5 )

);



// Define the number of random number sequences to analyze:

var N = 100;



// Initialize a counter for sequences satisfying the 5% threshold:

var count = 0;



// Perform analysis...

var bool;

var i;

for ( i = 0; i < N; i++ ) {

    bool = p( randu() );

    if ( bool ) {

        count += 1;

    }

    console.log( bool );

}

console.log( '%d of %d', count, N );

```



* * *



## See Also



-   [`@stdlib/iter-flow`][@stdlib/iter/flow]: create a fluent interface for chaining together iterator methods.

-   [`@stdlib/iter-pipeline-thunk`][@stdlib/iter/pipeline-thunk]: create an iterator thunk.



* * *



## Notice



This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].



#### Community



[![Chat][chat-image]][chat-url]



---



## License



See [LICENSE][stdlib-license].



## Copyright



Copyright © 2016-2024. The Stdlib [Authors][stdlib-authors].



[npm-image]: http://img.shields.io/npm/v/@stdlib/iter-pipeline.svg

[npm-url]: https://npmjs.org/package/@stdlib/iter-pipeline



[test-image]: https://github.com/stdlib-js/iter-pipeline/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/iter-pipeline/actions/workflows/test.yml?query=branch:main



[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/iter-pipeline/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/iter-pipeline?branch=main



[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg

[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im



[stdlib]: https://github.com/stdlib-js/stdlib



[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors



[umd]: https://github.com/umdjs/umd

[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules



[deno-url]: https://github.com/stdlib-js/iter-pipeline/tree/deno

[deno-readme]: https://github.com/stdlib-js/iter-pipeline/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/iter-pipeline/tree/umd

[umd-readme]: https://github.com/stdlib-js/iter-pipeline/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/iter-pipeline/tree/esm

[esm-readme]: https://github.com/stdlib-js/iter-pipeline/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/iter-pipeline/blob/main/branches.md



[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/iter-pipeline/main/LICENSE



[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol



[@stdlib/iter/flow]: https://github.com/stdlib-js/iter-flow



[@stdlib/iter/pipeline-thunk]: https://github.com/stdlib-js/iter-pipeline-thunk