Sort a 2d array by recurring ascending sequences of a column's values

Question

I have an Array that I need to sort, I will post an example for better understanding. This is my unsorted Array:

[0] => Array
    (
        [title] => This is some title
        [catid] => 1
    )    
[1] => Array
    (
        [title] => This is some title
        [catid] => 1
    )
[2] => Array
    (
        [title] => This is some title
        [catid] => 2
    )    
[3] => Array
    (
        [title] => This is some title
        [catid] => 2
    )

I need to re-sort it like this:

[0] => Array
    (
        [title] => This is some title
        [catid] => 1
    )    
[1] => Array
    (
        [title] => This is some title
        [catid] => 2
    )
[2] => Array
    (
        [title] => This is some title
        [catid] => 1
    )    
[3] => Array
    (
        [title] => This is some title
        [catid] => 2
    )

I'll have more that two categories and I need to select one item per category so if I have 3 categories, my catid in that case will be sorted like this:

catid: 1, 2, 3, 1, 2, 3

Answer 1

Here's my take:

/** just generating some data, not part of script **/
$originalArray = array();
$title = range('a','z');
for ($x=0;$x<20;$x++) {
  shuffle($title);
  $originalArray[] = array(
    'title' => implode(array_slice($title,0,rand(4,9))),
    'catid' => rand(1,3)
  );
}
/** end generating data **/


$tempArray = array();
foreach ($originalArray as $array) {
  $tempArray[$array['catid']][] = $array['title'];
}
ksort($tempArray);

$newArray = array();
while (count($tempArray)>0) {
  foreach ($tempArray as $mKey => &$mArray) {
    if (count($mArray)>0)
      $newArray[] = array('title'=>array_shift($mArray),'catid'=>$mKey);
  }
  $tempArray = array_filter($tempArray);
}