GoLang Ds\Map::reduce

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PHP Ds\Map::reduce

PHP original manual for Ds\Map::reduce [ show | php.net ]

Ds\Map::reduce

(PECL ds >= 1.0.0)

Ds\Map::reduce — Reduces the map to a single value using a callback function

Description

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

Reduces the map to a single value using a callback function.

Parameters

callback
mixed callback ( mixed $carry , mixed $key , mixed $value )
carry

The return value of the previous callback, or initial if it's the first iteration.

key

The key of the current iteration.

value

The value of the current iteration.

initial

The initial value of the carry value. Can be NULL.

Return Values

The return value of the final callback.

Examples

Example #1 Ds\Map::reduce() with initial value example

<?php
$map = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);

$callback = function($carry, $key, $value) {
    return $carry * $value;
};

var_dump($map->reduce($callback, 5));

// Iterations:
//
// $carry = $initial = 5
//
// $carry = $carry * 1 =  5
// $carry = $carry * 2 = 10
// $carry = $carry * 3 = 30
?>

The above example will output something similar to:

int(30)

Example #2 Ds\Map::reduce() without an initial value example

<?php
$map = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);

var_dump($map->reduce(function($carry, $key, $value) {
    return $carry + $value + 5;
}));

// Iterations:
//
// $carry = $initial = null
//
// $carry = $carry + 1 + 5 =  6
// $carry = $carry + 2 + 5 = 13
// $carry = $carry + 3 + 5 = 21
?>

The above example will output something similar to:

int(21)