CAKEPHP:How to compare common items between two arrays - cakephp

Question

How do I compare two arrays and list common items in a third array. I want to print the third array. Please help guys. My results are coming in two lists.
<?php
$appsubjects = $this->ProgrammeChoice->
ApplicantsDetail->ApplicantAlevelQualification->
find('list',array('fields'=> array('subject_code'),
'conditions'=>array('ApplicantAlevelQualification.applicants_detail_id'=>$app_id)));
$progrequirements[] =
$this->ProgrammeChoice->Programme->ProgrammeRequirementsSubject->
find('all',array('fields'= > array('programme_code','subject_code','programme_name','compulsory'),
'conditions'=>
array('subject_code'=>$s_code,'compulsory'=>'true')));
?>
So now i don't know how to get a 3rd list of items for which the subject_code is the same for Array(1) and Array(2), where compulsory is true.
The essence of my program is that I want applicants to enter their subjects, applying for different degree programs. Then for each degree there are subjects which are required(Array(2)), and some are compulsory. So my program should be able to list all degree programmes that matches the subjects entered. I hope you understand my question. Please help i'm stuck.

Answer 1

If I understood, I think you are doing it wrong. You make two database queries and after that you want find common items. How about doing it directly in query? :) is there some good reason not to?
edit: or make third query after user has submitted something. some ajax and voilá.

Answer 2

I am not going to go into why you may want to compare arrays or not. But indeed array manipulation skills could always come in handy.
CakePHP has the Set Array Management class. What you may need for finding differences in arrays is the Set::diff function. It "Computes the difference between a Set and an array, two Sets, or two arrays". The following example is from the CakePHP 2.0 Book:
<?php
$a = array(
0 => array('name' => 'main'),
1 => array('name' => 'about')
);
$b = array(
0 => array('name' => 'main'),
1 => array('name' => 'about'),
2 => array('name' => 'contact')
);
$result = Set::diff($a, $b);
/* $result now looks like:
Array
(
[2] => Array
(
[name] => contact
)
)
*/
$result = Set::diff($a, array());
/* $result now looks like:
Array
(
[0] => Array
(
[name] => main
)
[1] => Array
(
[name] => about
)
)
*/
$result = Set::diff(array(), $b);
/* $result now looks like:
Array
(
[0] => Array
(
[name] => main
)
[1] => Array
(
[name] => about
)
[2] => Array
(
[name] => contact
)
)
*/
$b = array(
0 => array('name' => 'me'),
1 => array('name' => 'about')
);
$result = Set::diff($a, $b);
/* $result now looks like:
Array
(
[0] => Array
(
[name] => main
)
)
*/
?>
Set also has other powerful utilities that I suggest you check out.
I use it all the time, when custom data manipulation is needed out side of the DB layer.