cuanyBy

Cumulatively test whether at least one element in a provided array passes a test implemented by a predicate function.

Installation

npm install @stdlib/array-base-cuany-by

Usage

var cuanyBy = require( '@stdlib/array-base-cuany-by' );

cuanyBy( x, predicate[, thisArg] )

Cumulatively tests whether at least one element in a provided array passes a test implemented by a predicate function.

function isPositive( value ) {
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];

var y = cuanyBy( x, isPositive );
// returns [ false, false, false, true, true ]

The predicate function is provided three arguments:

• value: current array element.
• index: current array element index.
• arr: input array.

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

function isPositive( value ) {
    this.count += 1;
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];

var context = {
    'count': 0
};

var out = cuanyBy( x, isPositive, context );
// returns [ false, false, false, true, true ]

var cnt = context.count;
// returns 4

cuanyBy.assign( x, out, stride, offset, predicate[, thisArg] )

Cumulatively tests whether at least one element in a provided array passes a test implemented by a predicate function and assigns results to a provided output array.

function isPositive( value ) {
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];
var y = [ false, null, false, null, false, null, false, null, false, null ];

var out = cuanyBy.assign( x, y, 2, 0, isPositive );
// returns [ false, null, false, null, false, null, true, null, true, null ]

var bool = ( out === y );
// returns true

The function supports the following parameters:

• x: input array.
• out: output array.
• stride: output array stride.
• offset: output array offset.
• predicate: test function.

Examples

var bernoulli = require( '@stdlib/random-array-bernoulli' );
var cuanyBy = require( '@stdlib/array-base-cuany-by' );

function isPositive( value ) {
    return ( value > 0 );
}

// Create an array of random values:
var x = bernoulli( 10, 0.1 );
console.log( x );

// Cumulatively determine whether at least one element is positive:
var out = cuanyBy( x, isPositive );
console.log( out );

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

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.