How to map multidimensional array - php

Question

I have an array of arrays that I need to consolidate into another array.
I have tried mapping over it, matching object_id, and gathering all account_ids for said object_id, but all my attempts are not even close as I am trying to learn PHP
This is the original array
[0] => Array
(
[rank] => 0
[id] => 6
[object_id] => 3
[account_id] => 13
)
[1] => Array
(
[rank] => 1
[id] => 7
[object_id] => 3
[account_id] => 565
)
[2] => Array
(
[rank] => 2
[id] => 1823
[object_id] => 825
[account_id] => 563
)
[3] => Array
(
[rank] => 3
[id] => 1824
[object_id] => 825
[account_id] => 564
)
[4] => Array
(
[rank] => 4
[id] => 1825
[object_id] => 825
[account_id] => 565
)
[5] => Array
(
[rank] => 5
[id] => 7187
[object_id] => 3113
[account_id] => 564
)
[6] => Array
(
[rank] => 6
[id] => 7188
[object_id] => 3113
[account_id] => 565
)
This is the desired result
[3] => [13, 565],
[825] => [563, 564, 565],
[3113] => [564, 565],

Answer 1

You need to create a new array by using object_id index.
Example:
<?
$array = array(
array('rank'=>0,'id'=>6,'object_id'=>3,'account_id'=>13),
array('rank'=>1,'id'=>7,'object_id'=>3,'account_id'=>565),
array('rank'=>2,'id'=>1823,'object_id'=>825,'account_id'=>563),
array('rank'=>3,'id'=>1824,'object_id'=>825,'account_id'=>564),
array('rank'=>4,'id'=>1825,'object_id'=>825,'account_id'=>565),
array('rank'=>5,'id'=>7187,'object_id'=>3113,'account_id'=>564),
array('rank'=>6,'id'=>7188,'object_id'=>3113,'account_id'=>565),
);
$newArray = array(); // initiliaze array
foreach ($array as $key => $value) {
$newArray[$value['object_id']][] = $value['account_id']; // save it in group
}
echo "<pre>";
print_r($newArray); // result
?>
Running Example