Ds\Deque::reduce
(PECL ds >= 1.0.0)
Ds\Deque::reduce — Reduces the deque to a single value using a callback function
説明
Reduces the deque to a single value using a callback function.
パラメータ
callback
-
carry
-
The return value of the previous callback, or
initial
if it's the first iteration. value
-
The value of the current iteration.
initial
-
The initial value of the carry value. Can be
null
.
戻り値
The return value of the final callback.
例
例1 Ds\Deque::reduce() with initial value example
<?php
$deque = new \Ds\Deque([1, 2, 3]);
$callback = function($carry, $value) {
return $carry * $value;
};
var_dump($deque->reduce($callback, 5));
// Iterations:
//
// $carry = $initial = 5
//
// $carry = $carry * 1 = 5
// $carry = $carry * 2 = 10
// $carry = $carry * 3 = 30
?>
上の例の出力は、 たとえば以下のようになります。
int(30)
例2 Ds\Deque::reduce() without an initial value example
<?php
$deque = new \Ds\Deque([1, 2, 3]);
var_dump($deque->reduce(function($carry, $value) {
return $carry + $value + 5;
}));
// Iterations:
//
// $carry = $initial = null
//
// $carry = $carry + 1 + 5 = 6
// $carry = $carry + 2 + 5 = 13
// $carry = $carry + 3 + 5 = 21
?>
上の例の出力は、 たとえば以下のようになります。
int(21)
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