; http://geocities.com/n8chz/tweak.txt

; Use of this file is ungoverned by the Cypherpunks Anti-License.
; Do with it as you will.

; Kitchen tested under
; Gnu Common Lisp
; version 2-2.2000000000000002

; the file referenced below is at
; http://geocities.com/n8chz/utgraph.txt

(load "utgraph.lsp")

; swap e1'th and e2'th elements of a list

(defun swap (e1 e2 liszt)
 (let
  ((n (length liszt)))
  (do
   ((k 0 (1+ k)))
   ((= k n) liszt)
   (cond
    ((equal e1 (nth k liszt))
     (setf (nth k liszt) e2))
    ((equal e2 (nth k liszt))
     (setf (nth k liszt) e1))))))

; swap two values in a
; midpoint partition
; generated by
; #'random-partition
; in "utgraph.lsp"
; "swap in randomized midpoint partition"

(defun sir-mpp (mpp)
 (let*
  ((n (length mpp))
   (i (random n))
   (jj (random (1- n)))
   (j (if (>= jj i) (1+ jj) jj))
   (dummy (nth i mpp)))
  (setf (nth i mpp) (nth j mpp))
  (setf (nth j mpp) dummy)
  mpp))

; swap values
; in a random embedding
; generated by #'random-init-embed
; (in "utgraph.lsp")

(defun swap-in-embed (embed)
 (transpose (mapcar #'sir-mpp (transpose embed))))

; do swap-in-embed on embed
; portion of graph structure
; as defined in "utgraph.lsp"

(defun swap-in-graph (graph)
 (setf (cdr graph) (swap-in-embed (cdr graph)))
 graph)

; brute force method for improving graphs
; using swap-in-graph
; this is notably slower than
; #'improve-graph
; (in "utgraph.lsp")

; for some reason it doesn't work

(defun iterate-graph (graph)
 (do*
  ((oldcorr (correlate-graph graph))
   (propose (swap-in-graph graph) (swap-in-graph propose)))
  ((< (correlate-graph propose) oldcorr) propose)))

; iterate graph n times
; write intermediate results
; to file named by 'filename

(defun ign (graph n filename)
 (do
  ((left n (1- left))
   (val graph (iterate-graph val))
   (stream (open filename :direction :output)))
  ((zerop left) (close stream) val)
  (print val stream)
  (print (cons left (correlate-graph val)))))