Get closest point to new point from a list

Hello everybody,

i have a list with coördinates called 'TESTLIST'

!testlist
((106213.0 507453.0 0.078) (106220.0 507452.0 0.12) (106229.0 507450.0 0.067) (106236.0 507449.0 0.082) (106242.0 507447.0 0.09) (106243.0 507447.0 0.096) (106244.0 507447.0 0.086) (106245.0 507446.0 0.088) (106251.0 507444.0 0.054) (106262.0 507440.0 0.113) (106272.0 507436.0 0.073) (106279.0 507433.0 0.151) (106288.0 507430.0 0.101) (106295.0 507427.0 0.176) (106303.0 507424.0 0.133) (106305.0 507423.0 0.133))

i have a coördinate:

(setq pt (getpoint))
click =>  (105810.0 507425.0 0.0)

How can i get the closest point to my 'pt', from the points in the list?

(setq closestpoint <point from list here>)

(setq rtnpt (car (vl-sort testlist (function (lambda ( a b ) (< (distance pt a) (distance pt b)))))))

Just a guess:

Using:

; Lee Mac
; http://www.cadtutor.net/forum/showthread.php?100467-Find-the-highest-and-lowest-mark-from-the-selected-quot-points-quot&p=683159
(defun extremum ( cmp lst / rtn ) 
 (setq rtn (car lst))
 (foreach itm (cdr lst) (if (apply cmp (list itm rtn)) (setq rtn itm)) )
 rtn
)

Then given a:

(setq p '(105810.0 507425.0 0.0))
(setq pL
 '((106213.0 507453.0 0.078) (106220.0 507452.0 0.12) (106229.0 507450.0 0.067) 
   (106236.0 507449.0 0.082) (106242.0 507447.0 0.09) (106243.0 507447.0 0.096) 
   (106244.0 507447.0 0.086) (106245.0 507446.0 0.088) (106251.0 507444.0 0.054) 
   (106262.0 507440.0 0.113) (106272.0 507436.0 0.073) (106279.0 507433.0 0.151) 
   (106288.0 507430.0 0.101) (106295.0 507427.0 0.176) (106303.0 507424.0 0.133) (106305.0 507423.0 0.133)
 )
)

Result is:

_$ (extremum 
 (function 
   (lambda (a b) 
     (< (apply '+ (mapcar 'abs (mapcar '- a p)))  (apply '+ (mapcar 'abs (mapcar '- b p))))
   )
 ) 
 pL
)
(106213.0 507453.0 0.078)
_$ 

And some more "clear" test:

(setq p '(0.0 0.0 0.0))
(setq pL
 '((1.0 1.0 30.0) (2.0 2.0 0.0) (3.0 3.0 0.0) 
   (4.0 4.0 0.0) (5.0 5.0 0.0) (6.0 6.0 0.0) 
 )
)

_$ (extremum 
 (function 
   (lambda (a b) 
     (< (apply '+ (mapcar 'abs (mapcar '- a p)))  (apply '+ (mapcar 'abs (mapcar '- b p))))
   )
 ) 
 pL
)
(2.0 2.0 0.0)

But I'm not 100% confident about this.

In plain autolisp, it could look like this :

[b][color=BLACK]([/color][/b]defun c:mindistp [b][color=FUCHSIA]([/color][/b]/ lst fp p d[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]setq lst '[b][color=NAVY]([/color][/b][b][color=MAROON]([/color][/b]10 20 10[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]12 20 8[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]30 15 1[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]40 24 6[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

 [b][color=FUCHSIA]([/color][/b]initget 1[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]setq fp [b][color=NAVY]([/color][/b]getpoint [color=#2f4f4f]"\nTest Point:   "[/color][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

 [b][color=FUCHSIA]([/color][/b]foreach p lst
     [b][color=NAVY]([/color][/b]cond [b][color=MAROON]([/color][/b][b][color=GREEN]([/color][/b]equal p fp 1e-8[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
           [b][color=MAROON]([/color][/b][b][color=GREEN]([/color][/b]not d[b][color=GREEN])[/color][/b]
            [b][color=GREEN]([/color][/b]setq d [b][color=BLUE]([/color][/b]distance fp p[b][color=BLUE])[/color][/b]
                  s p[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
           [b][color=MAROON]([/color][/b][b][color=GREEN]([/color][/b]< [b][color=BLUE]([/color][/b]distance fp p[b][color=BLUE])[/color][/b] d[b][color=GREEN])[/color][/b]
            [b][color=GREEN]([/color][/b]setq d [b][color=BLUE]([/color][/b]distance fp p[b][color=BLUE])[/color][/b]
                  s p[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

 [b][color=FUCHSIA]([/color][/b]prin1 [b][color=NAVY]([/color][/b]list d s[b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]prin1[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

-David

David's is the most efficient one, but mine although the slowest is the shortest one...

It's up to you what version you are to use...

Another:

; (car (ClosestFurthestPt p pL))
(defun ClosestFurthestPt ( p pL / L )
 (setq L (mapcar (function (lambda (x) (distance p x))) pL))
 (mapcar (function (lambda (x) (nth (vl-position (apply x L) L) pL))) '(min max))
)

Thanks all,

I used Marko's code. Did the job for me. And is very fast!

Thanks for the help!

Encountered a little problem:

I use this code, to get the closest point from 'testlist' to my current point 'pt' and set that point to 'rtnpt'....

(setq rtnpt (car (vl-sort testlist (function (lambda ( a b ) (< (distance pt a) (distance pt b)))))))

Sometimes, mt current point 'pt' is also in the testlist.... How can edit this code, so it checks for the closest point, and 'skips' if the found point is the current point...

Updated post 4

Sometimes plain AutoLisp can be modified so much easier than Visual Lisp routines

My &0.02 -David