@stdlib/iter-pipeline NPM

iterPipeline

Create an iterator pipeline.

Installation

npm install @stdlib/iter-pipeline

Usage

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

iterPipeline( iterFcn0[, ...iterFcn] )

Returns an iterator pipeline.

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 functions provided as separate arguments or as a single argument consisting of an array of iterator functions.

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 pipeline (as defined by this function), an iterator function is defined as a unary function which accepts an iterator as its only argument.
Each iterator function, except the last iterator function, within an iterator pipeline must return an iterator.
Starting from the left, each returned iterator is passed to the next iterator function.
The result of the last iterator function is the result of the pipeline.

Examples

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 );

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.