Ds\Map::reduce
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)
© 1997–2017 The PHP Documentation Group
Licensed under the Creative Commons Attribution License v3.0 or later.
https://secure.php.net/manual/en/ds-map.reduce.php