[permutation] how can I make all Instance combinations? 

Hi, I have a question with my skill language.

I wanna make permutation list with plural cell Instances.

For example , If I have a,b,c instances

 I wanna return list(a b c) list(a c b) list(b a c) list(b c a) list(c a b) list(c b a) => 3*2*1 lists!!

 I tried all day with

procedure(permutaion(()

prog(()

 Inst = list(a b c d)

foreach(***********)

)) but may be I'm not smart enogh to deal with this skill .....

somebody help  me out...

Hopefully this code will help you:

/* abPermutations.ils

Author     A.D.Beckett
Group      Custom IC (UK), Cadence Design Systems Ltd.
Language   SKILL
Date       Mar 28, 2012 
Modified   
By         

Generate permutations in lexical order

Almost certainly there's a fancier way to do this...

A few versions of doing this. One based on a perl algorithm (uses arrays), 
and the second two are more LISPy ways of doing this

Some of these functions require SKILL++ lexical scoping so please
ensure file keeps the ".ils" suffix

***************************************************

SCCS Info: @(#) abPermutations.ils 03/28/12.09:50:21 1.1

*/

(defun abPermutations (listOfObjects)
  (let (arrayOfObjects size indexArray)
    ;--------------------------------------------------------------------
    ; Convert everything to arrays to allow faster manipulation
    ;--------------------------------------------------------------------
    (setq arrayOfObjects (listToVector listOfObjects))
    (setq size (sub1 (length arrayOfObjects)))
    (setq indexArray (makeVector (add1 size)))
    (for i 0 size (setarray indexArray i i))
    ;--------------------------------------------------------------------
    ; Local function to swap two array entries
    ;--------------------------------------------------------------------
    (defun swap (a b)
      (let (tmp)
        (setq tmp (arrayref indexArray a))
        (setarray indexArray a (arrayref indexArray b))
        (setarray indexArray b tmp)
        )
      )
    ;--------------------------------------------------------------------
    ; Local function that can be called recursively to generate permutations
    ;--------------------------------------------------------------------
    (defun genPerm ()
      (let ((k (sub1 size)) (j size) retVal)
        (setq retVal (foreach mapcar ind (vectorToList indexArray)
                              (arrayref arrayOfObjects ind)))
        (while (and (geqp k 0) (greaterp (arrayref indexArray k) (arrayref indexArray (add1 k))))
               (postdecrement k))
        (if (minusp k)
          (list retVal)
          (progn
            (while (greaterp (arrayref indexArray k) (arrayref indexArray j))
                   (postdecrement j))
            (swap j (postincrement k))
            (setq j size)
            (while (greaterp j k)
                   (swap (postdecrement j) (postincrement k))
                   )
            (cons retVal (genPerm))
            )
          )
        )
      )

    (genPerm)
    )
  )

(defun abPerms (l)
  ;----------------------------------------------------------------------
  ; Local function to remove only the first match in a list
  ; which means that it copes with repeated values in the list
  ;----------------------------------------------------------------------
  (defun removeFirst (val l)
    (let (found)
      (setof elem l 
             (cond 
               (found t)
               ((equal val elem) (setq found t) nil)
               (t t)
               ))))
  (if (null l) '(nil)
    (mapcan (lambda (x)
              (mapcar (lambda (y) (cons x y))
                      (abPerms (removeFirst x l )))) l)))

(defun abPermsUniqueList (l)
  (if (null l) '(nil)
    (mapcan (lambda (x)
              (mapcar (lambda (y) (cons x y))
                      (abPermsUniqueList (remove x l )))) l)))

Wow!!! Thanks!!

This is exactily what I wanted!!

I just noticed that there's a typo in the comments of the file - it should really have a ".ils" suffix because some of the functions use SKILL++ lexical scoping - so my advice is that if you use this, please ensure that it has a .ils suffix.

I'll edit the post with the code to make this clearer.

Andrew.