PHP | Ds\Map reduce() Function

The Ds\Map::reduce() function is an inbuilt function in PHP which is used to reduce the map to a single value by applying operations using the callback function.

Syntax:

mixed public Ds\Map::reduce( $callback, $initial )

Parameter: This function accepts two parameters as mentioned above and described below:

  • $callback: This parameter holds the function which contains the operation on the elements and store carry. This callback function contains three arguments which are listed below:
    • carry: It holds the return value of the previous callback, or initial if it’s the first iteration.
    • key: It holds the key of the current iteration.
    • value: It holds the value of the current iteration.
  • $initial: This parameter holds the initial value of carry, which can be NULL.

Return value: This function returns the final value returned by the callback function.

Below programs illustrate the Ds\Map::reduce() function in PHP:

Program 1:

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php 
  
// Declare a new map
$map = new \Ds\Map(["a" => 1, "b" => 3, "c" => 5]); 
   
echo("Map Elements\n"); 
   
print_r($map); 
   
// Callback function with reduce function 
echo("\nElement after performing operation\n"); 
  
var_dump($map->reduce(function($carry, $key, $element) { 
    return $carry + $element + 2; 
})); 
   
?> 

chevron_right


Output:

Map Elements
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 1
        )

    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 3
        )

    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 5
        )

)

Element after performing operation
int(15)

Program 2:

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php 
   
// Declare new Map elements
$map = new \Ds\Map(["a" => 10, "b" => 20,
            "c" => 30, "d" => 40, "e" => 50]); 
   
echo("Original map elements\n"); 
   
print_r($map); 
   
$func_gfg = function($carry, $key, $element) { 
    return $carry * $element
}; 
   
echo("\nMap after reducing to single element\n"); 
   
// Use reduce() function 
var_dump($map->reduce($func_gfg, 10)); 
   
?> 

chevron_right


Output:

Original map elements
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 10
        )

    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 20
        )

    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 30
        )

    [3] => Ds\Pair Object
        (
            [key] => d
            [value] => 40
        )

    [4] => Ds\Pair Object
        (
            [key] => e
            [value] => 50
        )

)

Map after reducing to single element
int(120000000)

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



My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.