Ds\Map::reduce
PHP function
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(PECL ds >= 1.0.0)
Reduces the map to a single value using a callback function
Description
Ds\Map::reduce(callable $callback, [mixed $initial]): mixed
Reduces the map to a single value using a callback function.
Parameters
callback- callback(mixed $carry, mixed $key, mixed $value): mixed
carryThe return value of the previous callback, or
initialif it's the first iteration.keyThe key of the current iteration.
valueThe value of the current iteration.
initialThe initial value of the carry value. Can be null.
Return Values
The return value of the final callback.
Examples
Ds\Map::reduce() with initial value example
php
<?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:
output
int(30)Ds\Map::reduce() without an initial value example
php
<?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:
output
int(21)