@stdlib/iter-first

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iterFirst

Return the first iterated value.

Installation

npm install @stdlib/iter-first

Usage

var iterFirst = require( '@stdlib/iter-first' );

iterFirst( iterator )

Returns the first iterated value.

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

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

var v = iterFirst( arr );
// returns 1

If a provided iterator does not return any iterated values, the function returns undefined.

var iterEmpty = require( '@stdlib/iter-empty' );

var v = iterFirst( iterEmpty() );
// returns undefined

Notes

• The function does not consume an entire iterator before returning.

Examples

var randu = require( '@stdlib/random-iter-randu' );
var iterMap = require( '@stdlib/iter-map' );
var iterFirst = require( '@stdlib/iter-first' );

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 applies a threshold to generated numbers:
var miter = iterMap( riter, threshold );

// Return the first threshold result:
var bool = iterFirst( miter );
// returns <boolean>

console.log( bool );

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See Also

• @stdlib/iter-head: create an iterator which returns the first n values of a provided iterator.
• @stdlib/iter-last: consume an entire iterator and return the last iterated value.
• @stdlib/iter-nth: return the nth iterated 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.