(PECL ds >= 1.0.0)
Ds\Map::reduce — Reduces the map to a single value using a callback function
Reduces the map to a single value using a callback function.
callbackcarry
The return value of the previous callback, or initial if
it's the first iteration.
keyThe key of the current iteration.
valueThe value of the current iteration.
initial
The initial value of the carry value. Can be null.
The return value of the final callback.
Приклад #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
?>Поданий вище приклад виведе щось схоже на:
int(30)
Приклад #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
?>Поданий вище приклад виведе щось схоже на:
int(21)