PHP | DsMap filter() Function

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

Syntax:

Ds\Map 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 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 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

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PHP | Ds\Map filter() Function

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