Ds\Map::reduce
(PECL ds >= 1.0.0)
Ds\Map::reduce — Reduces the map to a single value using a callback function
Beschreibung
Reduces the map to a single value using a callback function.
Parameter-Liste
-
callback
-
-
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
.
Rückgabewerte
The return value of the final callback.
Beispiele
Beispiel #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
?>
Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:
int(30)
Beispiel #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
?>
Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:
int(21)