Get all combinations from multiple nested arrays

Question

I'm trying to come up with an algorithm in PHP to get all the combinations for a nested array:

Array
(
    [0] => Array
        (
            [0] => Option Object
                (
                    [strValue] => rough
                )

            [1] => Option Object
                (
                    [strValue] => smooth
                )

            [2] => Option Object
                (
                    [strValue] => coarse
                )

        )

    [1] => Array
        (
            [0] => Option Object
                (
                    [strValue] => shiney
                )

            [1] => Option Object
                (
                    [strValue] => mat
                )

        )

    [2] => Array
        (
            [0] => Option Object
                (
                    [strValue] => Large
                )

            [1] => Option Object
                (
                    [strValue] => Medium
                )

            [2] => Option Object
                (
                    [strValue] => Small
                )

            [3] => Option Object
                (
                    [strValue] => very large
                )

        )

)

So I would get something back like:

-rough, shiney, Large

-rough, shiney, Small

-rough, shiney, Medium

-rough, shiney, Very Large

-smooth, shiney, Large

-smooth, shiney, Small

-smooth, shiney, Medium

-smooth, shiney, Very Large

etc (should be 24 in this example)

I've tried through various foreach examples and some basic recursive function, but I seem to be getting no where fast. If anyone could give a basic outline of how to solve this I'd be very grateful, thanks!

Answer 1

I just wrote this, that works for arrays of any length..

<?php

function cartesian_product($a) {
  $result = array(array());
  foreach ($a as $list) {
    $_tmp = array();
    foreach ($result as $result_item) {
      foreach ($list as $list_item) {
        $_tmp[] = array_merge($result_item, array($list_item));
      }
    }
    $result = $_tmp;
  }
  return $result;
}


// Let's test this..                                                                                                                                                                                    

header('Content-type: text/plain');

$a = array(
  array('rough','smooth','coarse'),
  array('shiney','mat'),
  array('small','medium','large','x-large'),
);

$result = cartesian_product($a);
foreach ($result as $row) {
  print implode(", ", $row) ."\n";
}

edit: Improved the code a bit..