Center Point of Polar Array

Well done Lee!

I am attaching my solution below as it is different from what Lee has come up with. But keep in mind that both pieces of code return the center in block space coordinates. If the array is moved, rotated, scaled etc. the point will no longer match WCS coordinates. You can use Gile's excellent matrix code to translate it.

; (KGA_Sys_ArrayPolarCenter (car (entsel)))
(defun KGA_Sys_ArrayPolarCenter (enm / elst pt)
 (if
   (and
     (setq elst (entget enm))
     (vl-position '(0 . "INSERT") elst)
     (wcmatch (cdr (assoc 2 elst)) "`*[uu]*")
     (setq elst (cdr (member '(102 . "{ACAD_REACTORS") elst)))
     (= (caar elst) 330)
     (setq elst (entget (cdar elst)))
     (vl-position '(0 . "ACDBASSOCDEPENDENCY") elst) ; Required?
     (setq elst (entget (cdr (assoc 330 elst))))
     (vl-position '(0 . "ACDBASSOCACTION") elst) ; Required?
     (vl-position '(1 . "Radius") elst) ; Polar check.
   )
   (vl-some
     '(lambda (sub / elst)
       (if
         (and
           (= 360 (car sub))
           (setq elst (entget (cdr sub)))
           (vl-position '(0 . "ACDBASSOCVERTEXACTIONPARAM") elst)
           (vl-position '(1 . "Origin") elst)
         )
         (cdr (assoc 10 elst)) ; Point in block space.
       )
     )
     elst
   )
 )
)

Nice one Roy - good alternative solution.

Just digging around Lee.

Mind you I didn't find this 'digging down'. Instead I created an array with a know center, saved as DXF and looked for the coords in that file. Using the handle of the entity I was then able to 'dig up' in the dwg. This approach, although not very sophisticated, can be quite effective.

Just digging around Lee.

Mind you I didn't find this 'digging down'. Instead I created an array with a know center, saved as DXF and looked for the coords in that file. Using the handle of the entity I was then able to 'dig up' in the dwg. This approach, although not very sophisticated, can be quite effective.

Interesting approach, Roy.