countIfs

Perform element-wise evaluation of one or more input arrays according to provided predicate functions and count the number of elements for which all predicates respectively return true.

Installation

npm install @stdlib/array-base-count-ifs

Usage

var countIfs = require( '@stdlib/array-base-count-ifs' );

countIfs( x0, predicate0[, x1, predicate1[, x2, predicate2[, ...args]]] )

Performs element-wise evaluation of one or more input arrays according to provided predicate functions and counts the number of elements for which all predicates respectively return true.

function predicate0( value ) {
    return ( value > 0 );
}

function predicate1( value ) {
    return ( value < 3 );
}

var x0 = [ 0, 1, 0, 1, 2 ];
var x1 = [ 2, 3, 1, 2, 5 ];

var out = countIfs( x0, predicate0, x1, predicate1 );
// returns 1

The function has the following parameters:

• x0: first input array.
• predicate0: first predicate function.
• x1: second input array (optional).
• predicate1: second predicate function (optional).
• x2: third input array (optional).
• predicate2: third predicate function (optional).
• args: additional input arrays and corresponding predicate functions (optional).

Each predicate function is provided three arguments:

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

Notes

• The function assumes that all input arrays have the same length.
• The function supports array-like objects supporting the accessor protocol (e.g., Complex128Array, Complex64Array, etc).

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var isPositiveInteger = require( '@stdlib/assert-is-positive-integer' ).isPrimitive;
var isNegativeInteger = require( '@stdlib/assert-is-negative-integer' ).isPrimitive;
var naryFunction = require( '@stdlib/utils-nary-function' );
var countIfs = require( '@stdlib/array-base-count-ifs' );

var x = discreteUniform( 10, -5, 5, {
    'dtype': 'int32'
});
console.log( x );

var y = discreteUniform( 10, -5, 5, {
    'dtype': 'int32'
});
console.log( y );

var out = countIfs( x, naryFunction( isPositiveInteger, 1 ), y, naryFunction( isNegativeInteger, 1 ) );
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.