Pick a polyline and create a list of its coordinates

[richie_hodgson]

I have a little project that I need to get started, has anyone got a code snippet for turning a multi vertex polyline into a list of coordinates rather than out-putting them to a file.

[luvr.leo]

(defun c:56 (/ obj f_name f_zm ff )
(vl-load-com)
(while (not obj)
	(if (setq obj (car (entsel "\nPIK POLYLINE")))
		(if (not (wcmatch (cdr (assoc 0 (entget obj))) "LWPOLYLINE"))
			(setq obj nil)
		)
	)
)
(setq f_name (strcat (vla-get-path (vla-get-activedocument (vlax-get-acad-object))) "\\COOR_PLINE.txt"))
(if (findfile f_name)
	(progn
		(setq f_zm (strcat (vla-get-path (vla-get-activedocument (vlax-get-acad-object))) "\\C_z.txt"))
		(setq ff (open f_zm "w"))
		(princ (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= (car x) 10)) (entget obj))) ff)
		(princ "\n" ff)
		(close ff)
		(vl-file-copy f_zm f_name T)
		(vl-file-delete f_zm)
	)
	(progn
		(setq ff (open f_name "w"))
		(princ (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= (car x) 10)) (entget obj))) ff)
		(princ "\n" ff)
		(close ff)
	)
)
(princ)
)

[richie_hodgson]

So I asked if there was a way to create a list without outputting to a file, I am not seeing that happening here

[pbejse · Accepted solution]

For clarification. Are you refering to POLYLINE (3dpolyline) AKA Heave Polyline or LWPOLYLINE (lightweight poliline)

copy and paste this smippet onto your command prompt, select the entity in question  and tell me what you see

(cdr (assoc 0 (entget (Car (entsel)))))

[richie_hodgson]

Definitely a lwpolyline. By the look of above (setq pts (cdr (assoc.......) will get me what I want

[richie_hodgson]

I am going to do some tinkering with that list and would like to push the results back into the selected somehow, I am going to do some reading but is this a simple thing

[pbejse]

---

@richie_hodgson wrote:
Definitely a lwpolyline. By the look of above (setq pts (cdr (assoc.......) will get me what I want

---

Well not really, there's a couple of ways to retrieve the points. and here's one way

(defun c:pts (/ pl )
(and (setq pl (ssget '((0 . "LWPOLYLINE"))))
     (foreach itm
	(setq ptlist (mapcar 'cdr
				     (vl-remove-if-not
				       '(lambda	(x)
					  (= (car x) 10)
					)
				       (entget (ssname pl 0))
				     )
			     )
		)
       (print itm)
       )
     )
  (princ)
  )

[luvr.leo]

sorry for bad english. Lisp records the coordinates vertex in txt file, the file name coor_pline.txt in the same folder as the dwg file.

[braudpat]

Hello

The routine PTEXPORT does the job ...

http://www.dotsoft.com/freestuff.htm

[Kent1Cooper]

---

@richie_hodgson wrote:

.... has anyone got a code snippet for turning a multi vertex polyline into a list of coordinates ....

---

For a lightweight polyline, if you're in [or parallel to] the World Coordinate Systam and you can take a list that does not include Z coordinates:

(mapcar 'cdr

  (vl-remove-if-not '(lambda (x) (= (car x) 10))

    (entget (car (entsel "\nSelect lightweight Polyline: ")))

  )

)

If you need Z coordinates:

(setq
  edata (entget (car (entsel "\nSelect lightweight Polyline: ")))
  elev (cdr (assoc 38 edata))
)
(mapcar '(lambda (x) (append x (list elev))); add Z  coordinate to all
  (mapcar 'cdr
    (vl-remove-if-not '(lambda (y) (= (car y) 10)) edata)
  )
)

Add object-selection controls, etc.  Add (vl-load-com) if needed.

[rkmcswain]

I'll throw another variety out there. Should handle all polylines, splines, lines, arcs, & 3dfaces.

http://www.4d-technologies.com/techcenter/pl/pl_plist.lsp

It requires this function also:

http://www.4d-technologies.com/techcenter/list/li_item.lsp

[Kent1Cooper · Accepted solution]

---

@richie_hodgson wrote:
I am going to do some tinkering with that list and would like to push the results back into the selected somehow, ... is this a simple thing

---

For that, I would recommend using the 'Coordinates property of the Polyline as a VLA object.  That starts out with an un-differentiated list of numbers, X & Y [& Z  for other than LW Polylines] coordinate values in a continuous list.  You can break that up into points for the vertices, for example this way:

(vl-load-com); if needed

(defun C:CoordList (/ plent plobj coords num pt)
  (setq
    plent (car (entsel "\nSelect Polyline: "))
    plobj (vlax-ename->vla-object plent)
    coords (vlax-get plobj 'Coordinates); un-differentiated list of X Y [& Z if applicable] coordinate values
  ); setq
  (setq num (if (= (cdr (assoc 0 (entget plent))) "LWPOLYLINE") 2 3))

    ; LW Polylines have only X & Y; "heavy" 2D & 3D have X Y & Z
  (repeat (/ (length coords) num)
    (repeat num ; number of coordinates to separate into a point list
      (setq
        pt (append pt (list (car coords)))
        coords (cdr coords)
      )
    ); repeat
    (setq
      ptlist (cons pt ptlist); put that point into list of points
      pt nil ; reset for next point
    ); setq
  ); repeat
  (setq ptlist (reverse ptlist)); list of coordinates divided up into point lists
); defun

You can then mess with the values of the points in that list, and when you're done, conglomerate them back into an un-differentiated list of numbers with:

(setq coords (apply 'append ptlist))

Then [and this is the best part], you can just impose that adjusted list back on the Polyline:

(vlax-put plobj 'Coordinates coords)

It's much easier to do that than to try to [for example] interweave (assoc 10) vertex point locations in between segment width and bulge-factor entries in a LWPolyline's entity data list, or work through the separate entity names of the vertices in "heavy" 2D or 3D Polylines.  It works for any variety of Polyline, as long as you manipulate point values in the right number of coordinates, i.e. don't do something that would add a Z coordinate into adjusted vertex locations for a LWPolyline, or if your process results in that, strip it off before conglomerating the coordinates list again.

[phanaem]

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@richie_hodgson wrote:

I have a little project that I need to get started, has anyone got a code snippet for turning a multi vertex polyline into a list of coordinates rather than out-putting them to a file.

---

This will return a list of point in WCS. Note that for a closed polyline the start and the end point are the same and both are returned in the result list.

Works for light, heavy or 3D polylines. 

(defun pline_points (e / i r)
  (repeat
    (1+ (setq i (fix (vlax-curve-getendparam e))))
     (setq r (cons (vlax-curve-getpointatparam e i) r)
           i (1- i)
     )
  )
  r
)

 And here is a test function. Works on any UCS.

(defun c:test ( / ss)
  (if
    (setq ss (ssget ":E:S" '((0 . "*POLYLINE")
                             (-4 . "<NOT")
                               (-4 . "<OR")
                                 (-4 . "&=") (70 .  2);Curve-fit
                                 (-4 . "&=") (70 .  4);Spline-fit
                                 (-4 . "&=") (70 . 16);3D polygon mesh
                                 (-4 . "&=") (70 . 32);polygon mesh
                                 (-4 . "&=") (70 . 64);polyface mesh
                               (-4 . "OR>")
                             (-4 . "NOT>")
                             )
                    )
          )
    (foreach p (pline_points (ssname ss 0))
      (entmake
        (list
          '(0 . "POINT")
          (cons 10 p)
          )
        )
      )
    )
  (princ)
  )

[Lee_Mac]

FWIW, I believe this:

phanaem wrote:

'((0 . "*POLYLINE")
                             (-4 . "<NOT")
                               (-4 . "<OR")
                                 (-4 . "&=") (70 .  2);Curve-fit
                                 (-4 . "&=") (70 .  4);Spline-fit
                                 (-4 . "&=") (70 . 16);3D polygon mesh
                                 (-4 . "&=") (70 . 32);polygon mesh
                                 (-4 . "&=") (70 . 64);polyface mesh
                               (-4 . "OR>")
                             (-4 . "NOT>")
                             )
                    )

Could be written:

'((0 . "POLYLINE") (-4 . "<NOT") (-4 . "&") (70 . 118) (-4 . "NOT>"))

[phanaem]

You're right Lee. Thanks.

[doni49]

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@Lee_Mac wrote:

FWIW, I believe this:

@phanaem wrote:

'((0 . "*POLYLINE")
                             (-4 . "<NOT")
                               (-4 . "<OR")
                                 (-4 . "&=") (70 .  2);Curve-fit
                                 (-4 . "&=") (70 .  4);Spline-fit
                                 (-4 . "&=") (70 . 16);3D polygon mesh
                                 (-4 . "&=") (70 . 32);polygon mesh
                                 (-4 . "&=") (70 . 64);polyface mesh
                               (-4 . "OR>")
                             (-4 . "NOT>")
                             )
                    )

Could be written:

'((0 . "POLYLINE") (-4 . "<NOT") (-4 . "&") (70 . 118) (-4 . "NOT>"))

---

While it's a little shorter (less code), it makes it less obvious as to exactly what it's doing.  The first version explicity tells what is being excluded.  WIth the second version, you'd have to have understand binary to know what it's doing.