Ds\Map::reduce

(PECL ds >= 1.0.0)

Ds\Map::reduceReduces the map to a single value using a callback function

Descrizione

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

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

Elenco dei parametri

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

Valori restituiti

The return value of the final callback.

Esempi

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
?>

Il precedente esempio visualizzerĂ  qualcosa simile a:

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
?>

Il precedente esempio visualizzerĂ  qualcosa simile a:

int(21)
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