sort multidimensional array in php by key of inner array

Question

I want to sort the Job titles by timestamp "1357894278"

<?php
foreach( $jobs as &$job )
{
    $cj_date[] =  array( strtotime($job->date) => array( $job->title ));
}

foreach ($results['results'] as $result)
{
    $in_date[] = array ( strtotime($result['date']) => array ($result['jobtitle']) );
}

$ans[] = array_merge($cj_date,$in_date);

foreach($ans as $a)  
{
    ksort($a);
    print_r($a);
}
?>

By running this this script I got my output as following:

Array( [0] => Array
              ( [1352796106] => Array 
                                ( [0] => JobTitle_1 )
              )
       [1] => Array
              ( [1352745201] => Array 
                                ( [0] => JobTitle_2 )
              )
       [2] => Array
              ( [1357894278] => Array 
                                ( [0] => JobTitle_3 )
              )
      )

So How to sort the Job-Titles by 1352796106, 1352745201, 1357894278 Thanks! Wait for the help

Answer 1

Try this:

function compare($a, $b) {
    $ak = array_keys($a);
    $bk = array_keys($b);
    return ($ak[0] < $bk[0]) ? -1 : 1;
}

usort($ans, "compare");
var_dump($ans);

usort sorts by a custom comparison function.

Answer 2

I had a similar problem a while back. I had a much more complex structure. I ended up creating another array as my 'map', and I used it for sorting/indexing.

The new map array was a very simple structure that only contained necessary information about my other structure, just enough information to index quickly and to sort quickly as well.

I am sure there may be other solutions, but this worked for me because I had very large complex structures that will be more expensive to iterate throught if I did not have that extra map structure. It all comes down to you calcuating your time-cost and finding out if it is going to be expensive or not for you depending on the complexity and the size of your data types.