PHP | Ds\Map filter() Function

Last Updated : 20 Mar, 2023

The Ds\Map::filter() function is an inbuilt function in PHP which is used to create a new map using the filter function. Syntax:

 public Ds\Map::filter( $callback )

Parameters: It contains a single parameter $callback which is an optional parameter and it returns True if the value should be included, False otherwise. Return value: This function returns a new map containing all the pairs for which either the callback returned True or all values that convert to True if a callback was not provided. Below programs illustrate the Ds\Map::filter() function in PHP: Program 1:

php

<?php  // PHP program to illustrate the filter()  // function of Ds\map   // Creating a Map  $map = new \Ds\Map([     1 => "Welcome",     2 => "to",     3 => "Geeks",       4 => "for",     5 => "Geeks"]);               // Display new sequence using filter function  var_dump($map->filter(function($key, $val) {      return $key % 3 == 0;  }));   ?>

Output:

object(Ds\Map)#3 (1) {   [0]=>   object(Ds\Pair)#2 (2) {     ["key"]=>     int(3)     ["value"]=>     string(5) "Geeks"   } }

Program 2:

php

<?php  // PHP program to illustrate the filter()  // function of Ds\map   // Creating a Map  $map = new \Ds\Map([         1 => 10,          2 => 20,         3 => 30,          4 => 40,         5 => 50]);               // Display new sequence using filter function  var_dump($map->filter(function($key, $val) {      return $val % 20 == 0;  }));   ?>

Output:

object(Ds\Map)#3 (2) {   [0]=>   object(Ds\Pair)#2 (2) {     ["key"]=>     int(2)     ["value"]=>     int(20)   }   [1]=>   object(Ds\Pair)#4 (2) {     ["key"]=>     int(4)     ["value"]=>     int(40)   } }

Reference: https://www.php.net/manual/en/ds-map.filter.php