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filter

Return a shallow copy of an array containing only those elements which pass a test implemented by a predicate function.

Usage

import filter from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-filter@deno/mod.js';

The previous example will load the latest bundled code from the deno branch. Alternatively, you may load a specific version by loading the file from one of the tagged bundles. For example,

import filter from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-filter@v0.2.2-deno/mod.js';

filter( x, predicate[, thisArg] )

Returns a shallow copy of an array containing only those elements which pass a test implemented by a predicate function.

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

var x = [ 1, -2, -3, 4 ];

var out = filter( x, isPositive );
// returns [ 1, 4 ]

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

var x = [ 1, 2, -3, 4 ];

var context = {
    'count': 0
};

var out = filter( x, predicate, context );
// returns [ 1, 2, 4 ]

var cnt = context.count;
// returns 4

Notes

• If provided an array-like object having a filter method, the function defers execution to that method and assumes that the method API has the following signature:

  x.filter( predicate, thisArg )
  

• If provided an array-like object without a filter method, the function performs a linear scan and always returns a generic array.

Examples

import discreteUniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-array-discrete-uniform@deno/mod.js';
var isPositiveInteger = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/assert-is-positive-integer' ).isPrimitive;
import naryFunction from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-nary-function@deno/mod.js';
import filter from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-filter@deno/mod.js';

var x = discreteUniform( 10, -5, 5, {
    'dtype': 'int32'
});
// returns <Int32Array>

var out = filter( x, naryFunction( isPositiveInteger, 1 ) );
// returns <Int32Array>

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Notice

This package is part of stdlib, a standard library 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.