;+
; NAME:
;	unique_only
; PURPOSE:
;	Return unique elements in array
; CATEGORY:
;	gen/pro/toolbox
; CALLING SEQUENCE:
	FUNCTION unique_only, tmp
; INPUTS:
;	tmp		array; type: any
; OUTPUTS:
;	R		indices of unique elements in
;			the same order as in the input
;			array.
; INCLUDE:
	@compile_opt.pro		; On error, return to caller
; PROCEDURE:
;	The difference with the IDL uniq function is that
;	the order of the elements in the original array
;	is retained:
;	IDL> a = [2,1]
;	IDL> print, a[uniq(a,sort(a))]
;       1       2
;	print, a[unique_only(a)]
;       2       1
; MODIFICATION HISTORY:
;	FEB-2007, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
;-

i = sort(tmp)
i = i[uniq(tmp,i)]

RETURN, i  &  END