PHP - Ds Map filter() Function

Ds\Map::filter() function can create a new map by using a callable to determine which pairs to include.

Syntax

public Ds\Map Ds\Map::filter([ callable $callback ] )

Ds\Map::filter() function can return a new map that contains all pairs for which either a callback return true, or all values that convert to true if a callback was not provided.

Example 1

<?php  
   $map = new \Ds\Map([1 => 10, 2 => 20, 3 => 30, 4 => 40, 5 => 50]);  
              
   var_dump($map->filter(function($key, $val) {  
      return $val % 20 == 0;  
   }));  
?> 

Example 2

<?php 
   $map = new \Ds\Map([1 => "Tutorials", 2 => "Point", 3 => "India", 4 => "Tutorix", 5 => "India"]); 
   
   var_dump($map->filter(function($key, $val) {
      return $key % 3 == 0;  
   }));  
?>