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Ds\Vector::reduce

PHP function Edit on GitHub ✎

(PECL ds >= 1.0.0)

Reduces the vector to a single value using a callback function

Description

Ds\Vector::reduce(callable $callback, [mixed $initial]): mixed

Reduces the vector to a single value using a callback function.

Parameters

callback

callback(mixed $carry, mixed $value): mixed

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.

Return Values

The return value of the final callback.

Examples

Ds\Vector::reduce() with initial value example

php

<?php
$vector = new \Ds\Vector([1, 2, 3]);

$callback = function($carry, $value) {
    return $carry * $value;
};

var_dump($vector->reduce($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\Vector::reduce() without an initial value example

php

<?php
$vector = new \Ds\Vector([1, 2, 3]);

var_dump($vector->reduce(function($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
?>

The above example will output something similar to:

output

int(21)

Source: reference/ds/ds/vector/reduce.xml · from the official PHP manual (php/doc-en)