PHP Array_intersect on multidimensional array with unknown number of keys

Question

I'm trying to make advanced search filters in an application that holds resources (people). I've got all the results in 1 multidimensional array. A user of the application can search for the persons Job title, skills, work field and country.

I've already made the part where I look up the people that meet the criteria given by the user. These results are stored in a multidimensional array. If the user is looking for someone with a specific resource with a job title and a specific skill the return value is this:

$realfilters = array(2) {
["resourcesWithJobtitle"]=> array(6) {
   [0]=> string(1) "1"
   [1]=> string(2) "48"
   [2]=> string(2) "88"
}
["resourcesWithSkill"]=> array(9) {
   [0]=> string(1) "4"
   [1]=> string(1) "8"
   [2]=> string(1) "48"
   [3]=> string(2) "50"
}

When the user also looks for a work field this is added to the result:

["resourcesWithWorkfield"]=> array(3) {
   [0]=> string(2) "48"
   [1]=> string(2) "96"
   [2]=> string(2) "97"
}

I need to know which resources meet all dimensions of the array so I can display them. (So in this example I need an array with just 1 value: 48). I think I need to use array_intersect but can't seem to get it right.

score 4 · Accepted Answer · edited Oct 01 '12 at 11:48

4

One of the possible solutions: you may first extract() the $realfilters array values to variables, and then apply the array_intersect() to them. But this solution is applicable only if there are not many possible filters.

Another one and probably the best solution would be to intersect in a loop, something like:

$res_arr = array_shift($realfilters);
foreach($realfilters as $filter){
     $res_arr = array_intersect($res_arr, $filter);
}

edited Oct 01 '12 at 11:48

user2428118

7,935
4
45
72

answered Jun 08 '12 at 14:31

Alexander Gilmanov

387
2
9

Seems like the way to go but isn't working: [code]if(!empty($realfilters)) { $resourceIDsThatMatchAllCritera = $realfilters[0]; for ($i = 1; $i < count($realfilters); $i++) { $resourceIDsThatMatchAllCritera = array_intersect_key($resourceIDsThatMatchAllCritera, $realfilters[$i]); } var_dump($resourceIDsThatMatchAllCritera); // empty }[/code] – Mettin Parzinski Jun 08 '12 at 14:53
1

Got it. $realfilters[0] doesn't work. Changed it to $realfilters["resourcesWithJobtitle"] and now it works! – Mettin Parzinski Jun 08 '12 at 15:32
Yeah. Just noticed that also :) But better solution just came to my mind (in case you don't know the key): $resourceIDsThatMatchAllCritera = array_shift($realfilters); foreach($realfilters as $filter){ $resourceIDsThatMatchAllCritera = array_intersect($resourceIDsThatMatchAllCritera, $filter); } – Alexander Gilmanov Jun 08 '12 at 15:35
@MettinParzinski by the way, why do you use array_intersect_key? keys are just indexes (0,1,2) in your case... – Alexander Gilmanov Jun 08 '12 at 15:40
That's a mistake. This is my final code: if(!empty($realfilters)) { $resourceIDsThatMatchAllCritera = $allResourceIDs; foreach ($realfilters as $key => $value) { $resourceIDsThatMatchAllCritera = array_intersect($resourceIDsThatMatchAllCritera, $realfilters[$key]); } } – Mettin Parzinski Jun 09 '12 at 12:21
OK, I see. Anyway, I think that the most clean & nice and also universal solution was offered by @chris :) – Alexander Gilmanov Jun 09 '12 at 12:27

goat · Answer 2 · 2012-06-08T15:42:53.643

$intersection = call_user_func_array('array_intersect', $array);

That will give you the elements present in all the sub arrays of $array.

edit- This above is like a shortcut for writing:

$intersection = array_intersect($array['a'], $array['b'], ...and so on for all elements...);

A loop could be used as well

$intersection = reset($array);
foreach ($array as $subarr) {
    $intersection = array_intersect($intersection, $subarr);
}
print_r($intersection);

PHP Array_intersect on multidimensional array with unknown number of keys

2 Answers2

Linked