[R] sorting without order

[Marc Mamin]

Hello,


In order to increase the performance of a script I'd like to sort very large vectors containing repeated integer values. 
I'm not interesting in having the values sorted, but only grouped.
I also need the equivalent of index.return from the standard "sort" function:

  f(c(10,1,10,100,1,10))

  =>

  grouped: c(10,10,10,1,1,100)
  ix:	  c(1,3,6,2,5,4)


is there a way to achieve this which would be faster than the standard sort function?

Thanks for any hints,

Marc Mamin