How to generate in PHP all combinations of items in multiple arrays

Here is recursive solution:

function combinations($arrays, $i = 0) {    if (!isset($arrays[$i])) {        return array();    }    if ($i == count($arrays) - 1) {        return $arrays[$i];    }    // get combinations from subsequent arrays    $tmp = combinations($arrays, $i + 1);    $result = array();    // concat each array from tmp with each element from $arrays[$i]    foreach ($arrays[$i] as $v) {        foreach ($tmp as $t) {            $result[] = is_array($t) ?                 array_merge(array($v), $t) :                array($v, $t);        }    }    return $result;}print_r(    combinations(        array(            array('A1','A2','A3'),             array('B1','B2','B3'),             array('C1','C2')        )    ));

This is a cartesian product, and I just asked the same question not too long ago. Here is the algorithm that is posted on the PHP website.

function array_cartesian_product($arrays){    $result = array();    $arrays = array_values($arrays);    $sizeIn = sizeof($arrays);    $size = $sizeIn > 0 ? 1 : 0;    foreach ($arrays as $array)        $size = $size * sizeof($array);    for ($i = 0; $i < $size; $i ++)    {        $result[$i] = array();        for ($j = 0; $j < $sizeIn; $j ++)            array_push($result[$i], current($arrays[$j]));        for ($j = ($sizeIn -1); $j >= 0; $j --)        {            if (next($arrays[$j]))                break;            elseif (isset ($arrays[$j]))                reset($arrays[$j]);        }    }    return $result;}

This code besides simplicity, get all combinations of multiple arrays and preserves keys.

function get_combinations($arrays) {    $result = array(array());    foreach ($arrays as $property => $property_values) {        $tmp = array();        foreach ($result as $result_item) {            foreach ($property_values as $property_key => $property_value) {                $tmp[] = $result_item + array($property_key => $property_value);            }        }        $result = $tmp;    }    return $result;}

Exemple:

Array(    Array    (        '1' => 'White',        '2' => 'Green',        '3' => 'Blue'    ),    Array    (        '4' =>' Small',        '5' => 'Big'    ))

Will return:

Array(    [0] => Array    (        [1] => White        [4] =>  Small    )    [1] => Array    (        [1] => White        [5] => Big    )    [2] => Array    (        [2] => Green        [4] =>  Small    )    [3] => Array    (        [2] => Green        [5] => Big    )    [4] => Array    (        [3] => Blue        [4] =>  Small    )    [5] => Array    (        [3] => Blue        [5] => Big    ))