PHP Sort a multidimensional array by number of items

Question

I have an array such as:

Array (     [DEF] => Array         (             [0] => Array                 (                     [type] => 1                     [id] => 1212                     [name] => Jane Doe                     [current] => 1                 )              [1] => Array                 (                     [type] => 1                     [id] => 3123121                     [name] => Door                     [current] =>                  )         )      [ABC] => Array         (             [0] => Array                 (                     [type] => 1                     [id] => 1234                     [name] => John Doe                     [current] =>                  )         )      [WW] => Array         (             [0] => Array                 (                     [type] => 1                     [id] => 1212                     [name] => Jane Doe                     [current] => 1                 )              [1] => Array                 (                     [type] => 1                     [id] => 3123121                     [name] => Door                     [current] =>                  )              [2] => Array                 (                     [type] => 1                     [id] => 64646                     [name] => Floor                     [current] =>                  )         ) ) 

And I want to sort this array by number ( count() ) of inner-array items descending (i.e. most items first), so I will have this array:

Array (     [WW] => Array         (             [0] => Array                 (                     [type] => 1                     [id] => 1212                     [name] => Jane Doe                     [current] => 1                 )              [1] => Array                 (                     [type] => 1                     [id] => 3123121                     [name] => Door                     [current] =>                  )              [2] => Array                 (                     [type] => 1                     [id] => 64646                     [name] => Floor                     [current] =>                  )         )      [DEF] => Array         (             [0] => Array                 (                     [type] => 1                     [id] => 1212                     [name] => Jane Doe                     [current] => 1                 )              [1] => Array                 (                     [type] => 1                     [id] => 3123121                     [name] => Door                     [current] =>                  )         )      [ABC] => Array         (             [0] => Array                 (                     [type] => 1                     [id] => 1234                     [name] => John Doe                     [current] =>                  )         ) ) 

Can anyone suggest an efficient way to do so? Thanks.

Answer 1

Using uksort:

uksort($array, function($a, $b) { return count($b) - count($a); }); 

Using array_multisort:

array_multisort(array_map('count', $array), SORT_DESC, $array); 

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With PHP < 5.3:

function sort_cb($a, $b) {     return count($b) - count($a); } uksort($array, 'sort_cb');