Topic: entmod question

[ronjonp]

Hey guys (and gals),

How would I replace a known vertex in a polyline (10 x x) in a list using entmod? From what I've read, entmod replaces the first (10 x x) found.

• (-1 . <Entity name: 7efb4550>)
[1] (0 . "LWPOLYLINE")
[2] (330 . <Entity name: 7efb2d18>)
[3] (5 . "11A")
[4] (100 . "AcDbEntity")
[5] (67 . 0)
[6] (410 . "Model")
[7] (8 . "0")
[8] (100 . "AcDbPolyline")
[9] (90 . 2)
[10] (70 . 128)
[11] (43 . 0.0)
[12] (38 . 0.0)
[13] (39 . 0.0)
[14] (10 6.00998 5.60127)
[15] (40 . 0.0)
[16] (41 . 0.0)
[17] (42 . 0.0)

[18] (10 13.5462 1.82911)
[19] (40 . 0.0)
[20] (41 . 0.0)
[21] (42 . 0.0)
[22] (210 0.0 0.0 1.0)

I would like to replace the bold rather than the (10 6.00998 5.60127) in the [14] spot.

Thanks,

Ron

[Keith™]

You would need to manipulate the list a tidbit to do what you want.

Lets say you you want to replace the second group 10 in a list, you could use something like this

entlist is your lwpolyline list and pnt is your new point

Code: [Select]

(entmod
   (subst
      (cons 10 pnt) ;<-- your new point
      (assoc 10
         (cdr         
            (member
               (assoc 10 entlist)
               entlist
            )
         )
      )
      entlist
   )
)

Now this of course will only change the second group 10, you can make the lisp loop through the entire list of DXF 10 groups by using something like this

"item" is the number of the item you want to retrieve

Code: [Select]

(setq newlist entlist x 0)
(while (< x item)
   (setq newlist
      (cdr
         (member
            (assoc 10 newlist)
          newlist
         )
      )
   )
   (setq x (1+ x))
)

None of this has been tested and it can also be done more efficiently in other manners, but I wanted you to get the understanding of how to accomplish it first.

[ronjonp]

Thanks Keith...I'll try and get this to work.

[T.Willey]

I think you have to use a foreach loop, and test each dxf list to compare it to the one known.  I have run into problems when with trying to substitute associated list when there are real numbers involved.  How I would do it.

Code: [Select]

(foreach lst EntData
 (if (equal lst '(10 x.x x.x x.x) 0.0001)
  (setq NewEntData (append NewEntData (list '(10 x.x x.x x.x))))
  (setq NewEntData (append NewEntData (list lst)))
 )
)


[ronjonp]

Thanks Tim. I think adding that fuzz factor fixed my problems

[T.Willey]

You're welcome.

[CAB]

I like it Tim. Here is the mapcar version.

Code: [Select]

(setq elst (mapcar '(lambda (x) (if (equal x OldVal 0.0001) NewVal x)) elst))

[T.Willey]

I like it Tim. Here is the mapcar version.

Code: [Select]

(setq elst (mapcar '(lambda (x) (if (equal x OldVal 0.0001) NewVal x)) elst))

I like that version better Alan!    Must have been to early in the morning on my first post.