PHP数组转化有关问题

PHP数组转化问题
Array
(
  [0] => Array
  (
  [0] => user-
  [1] => notice-
  )

  [1] => Array
  (
  [0] => user-
  [1] => calendar-
  [2] => calendar-
  )

  [2] => Array
  (
  [0] => notice-
  [1] => calendar-
  )

)
想要的效果

Array([0]=>'user-notice',[1]=>'user-calendar-calendar',[2]=>'user-calendar')

------解决方案--------------------

PHP code

foreach($arr as $v) $ar[]=substr(join('',$v),0,-1);
print_r($ar);