$a=array (
  0 => 9,
  1 => 12,
  2 => 23,
  3 => 4,
  4 => -15,
);
$b=array (
  0 => 9,
  1 => 22,
  2 => 3,
  3 => 4,
  4 => -15,
);
array(2) {
  [1]=>
  int(12)
  [2]=>
  int(23)
}
$a=array (
  '0.1' => 
  cr::__set_state(array(
     'a' => 9,
  )),
  '0.5' => 
  cr::__set_state(array(
     'a' => 12,
  )),
  0 => 
  cr::__set_state(array(
     'a' => 23,
  )),
  1 => 
  cr::__set_state(array(
     'a' => 4,
  )),
  2 => 
  cr::__set_state(array(
     'a' => -15,
  )),
);
$b=array (
  '0.1' => 
  cr::__set_state(array(
     'a' => 9,
  )),
  '0.5' => 
  cr::__set_state(array(
     'a' => 22,
  )),
  0 => 
  cr::__set_state(array(
     'a' => 3,
  )),
  1 => 
  cr::__set_state(array(
     'a' => 4,
  )),
  2 => 
  cr::__set_state(array(
     'a' => -15,
  )),
);
array(2) {
  ["0.5"]=>
  object(cr)#2 (1) {
    ["a"]=>
    int(12)
  }
  [0]=>
  object(cr)#3 (1) {
    ["a"]=>
    int(23)
  }
}