merge two keys on different identical keys in a multidimensional array - php

Question

I have a single multidimensional array that I'm trying to merge keys. I'd like to merge where identical keys occur on a separate key from the one I'm trying to merge.
My current array looks like so.
Array
(
[0] => Array
(
[zone_id] => 2
[zone_title] => Users
[link_title] => Users
)
[1] => Array
(
[zone_id] => 2
[zone_title] => Users
[link_title] => Add User
)
[2] => Array
(
[zone_id] => 3
[zone_title] => Locations
[link_title] =>
)
)
I would like to leave the array as is with the exception of merging together arrays that have identical zone_id keys.
Result
Array
(
[0] => Array
(
[zone_id] => 2
[zone_title] => Users
[link_title] => Array
(
[0] => Users
[1] => Add user
)
)
[1] => Array
(
[zone_id] => 3
[zone_title] => Locations
[link_title] =>
)
)

Answer 1

<?php
function merge_keys($arr){
for ($key = 0; $key < count($arr); $key++) {
$zone_id = $arr[$key]['zone_id'];
$index = search($arr, $zone_id);
if ($index != $key && $index != -1){
$link_title = $arr[$key]['link_title'];
$link_title2 = $arr[$index]['link_title'];
$arr[$key]['zone_id'] = $zone_id;
$arr[$key]['zone_title'] = $arr[$key]['zone_title'];
$arr[$key]['link_title'] = array($link_title, $link_title2);
unset($arr[$index]);
}
}
return $arr;
}
function search($arr, $zone_id){
for ($i = count($arr) - 1; $i >= 0 ; $i--) {
$item = $arr[$i];
$tmp_zone_id = $item['zone_id'];
if($tmp_zone_id == $zone_id){
return $i;
}
}
return -1;
}
$arr = array(array('zone_id' => 2, 'zone_title' => 'Users', 'link_title' => 'Users'),
array('zone_id' => 2, 'zone_title' => 'Users', 'link_title' => 'Add User'),
array('zone_id' => 3, 'zone_title' => 'Locations', 'link_title' => ''));
echo "Before change: \n";
print_r($arr);
$arr = merge_keys($arr);
echo "After change: \n\n";
print_r($arr);
?>