If this is the same issue as addressed in this recent thread of yours? If so, my suggestion that you should instead be using an array of objects instead of an array of arrays still stands.
If you still insist on using an array of arrays, then the first thing you need to determine is whether the top-level array index will be meaningful, i.e. it's not just an arbitrary number but represents something about that sub-array (database primary key, product ID, etc.), or if it will just be a sequential array index such as you get using the $myArray[] = array(1,2,3); syntax.