Build associative array based on values of another associative array

Question

I'm looking for an elegant way to turn this array:

Array (
  [foo] => 1
  [bar] => 1
  [zim] => 3
  [dib] => 6
  [gir] => 1
  [gaz] => 3
)

Into this array:

Array (
  [1] => Array ( foo, bar, gir ),
  [3] => Array ( zim, gaz ),
  [6] => Array ( dib )
)

Note:, there is no relationship between the keys or values. They are completely arbitrary and used as examples only. The resulting array should be an associative array grouped by the values of the input array.

Thanks!

Answer 1

$input = array(
  'foo' => 1,
  'bar' => 1,
  'zim' => 3,
  'dib' => 6,
  'gir' => 1,
  'gaz' => 3
)

$output = array();
foreach ( $input as $k => $v ) {
  if ( !isset($output[$v]) ) {
    $output[$v] = array();
  }

  $output[$v][] = $k;
}

Answer 2

I think this will do it just fine:

foreach ($arr1 as $k => $val) $arr2[$val][] = $k;

where $arr1 is the original array outputting the new array to $arr2.