README.md

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iterCuNoneBy

Create an iterator which cumulatively tests whether every iterated value fails a test implemented by a predicate function.

Installation

npm install @stdlib/iter-cunone-by

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 iterCuNoneBy = require( '@stdlib/iter-cunone-by' );

iterCuNoneBy( iterator, predicate[, thisArg] )

Returns an iterator which cumulatively tests whether every iterated value fails a test implemented by a predicate function.

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

function predicate( v ) {
    return ( v > 0 );
}

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

var it = iterCuNoneBy( arr, predicate );

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

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

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

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

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

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

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.

A predicate function is provided two arguments:

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

To set the predicate function execution context, provide a thisArg.

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

function predicate( v ) {
    this.count += 1;
    return ( v < 0 );
}

var ctx = {
    'count': 0
};

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

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

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

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

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

var count = ctx.count;
// returns 4

Notes

• A predicate function is invoked for each iterated value until the first truthy predicate function return value. Upon encountering the first truthy return value, the returned iterator ceases to invoke the predicate function and returns false for each subsequent iterated value of the provided input iterator.

Examples

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

function threshold( r ) {
    return ( r > 0.95 );
}

// Create an iterator which generates uniformly distributed pseudorandom numbers:
var opts = {
    'iter': 100
};
var riter = randu( opts );

// Create an iterator which cumulatively tests whether every iterated value fails a test:
var it = iterCuNoneBy( riter, threshold );

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

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.