unista Interface

unique(3f) - [M_orderpack:UNIQUE] removes duplicates from an array
             otherwise retaining original order (i.e. it is "stable")

 Subroutine Unique (INOUTVALS, NUNI)

  ${TYPE} (kind=${KIND}), Intent (InOut) :: INOUTVALS(:)
  Integer, Intent (Out)                  :: NUNI

Where ${TYPE}(kind=${KIND}) may be

   o Real(kind=real32)
   o Real(kind=real64)
   o Integer(kind=int32)
   o Character(kind=selected_char_kind("DEFAULT"),len=*)

UNIQUE(3f) does a stable removal of duplicates from an array.

It leaves in the initial set only those entries that are unique,
packing the array, and leaving the order of the retained values
unchanged.

Internally this subroutine uses Merge-sort unique inverse ranking.

 INOUTVALS   input array to reduce to unique values
 NUNI    number of values comprising the returned set of unique
         values

program demo_unique
! remove duplicates with remaining elements remaining in initial order
use M_orderpack, only : unique
implicit none
character(len=*),parameter :: list= '(*(g0:,", "))'
integer :: nuni

int : block
integer,allocatable :: INOUTVALS(:)
 INOUTVALS=[44,33,33,33,22,11,33,44,55,33]
 print list,'ORIGINAL:',INOUTVALS
 call unique(INOUTVALS,nuni)
 INOUTVALS=INOUTVALS(:nuni)
 print list,'UNIQUE:',INOUTVALS
endblock int

end program demo_unique

ORIGINAL:, 44, 33, 33, 33, 22, 11, 33, 44, 55, 33
UNIQUE:, 44, 33, 22, 11, 55

Michel Olagnon - Feb. 2000

John Urban, 2022.04.16

CC0-1.0