@stdlib/iter-some-by

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iterSomeBy

Test whether at least n iterated values pass a test implemented by a predicate function.

Installation

npm install @stdlib/iter-some-by

Usage

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

iterSomeBy( iterator, n, predicate[, thisArg] )

Tests whether at least n iterated values pass a test implemented by a predicate function.

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

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

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

var bool = iterSomeBy( arr, 4, predicate );
// returns true

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

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

function predicate() {
    return true;
}

var bool = iterSomeBy( array2iterator( [] ), 1, predicate );
// returns false

A predicate function is provided two arguments:

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

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

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

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

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

var ctx = {
    'count': 0
};

var bool = iterSomeBy( arr, 3, predicate, ctx );
// returns true

var n = ctx.count;
// returns 4

Notes

• The function immediately returns upon encountering n truthy return values.

Examples

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

// Determine if at least 5 values exceed a threshold:
var bool = iterSomeBy( riter, 5, threshold );
// returns <boolean>

console.log( bool );

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See Also

• @stdlib/iter-any-by: test whether at least one iterated value passes a test implemented by a predicate function.
• @stdlib/iter-every-by: test whether every iterated value passes a test implemented by a predicate function.
• @stdlib/iter-for-each: create an iterator which invokes a function for each iterated value before returning the iterated value.
• @stdlib/iter-none-by: test whether every iterated value fails a test implemented by a predicate function.
• @stdlib/iter-some: test whether at least n iterated values are truthy.

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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.