Topic: Comparing List of Points

[cmwade77]

Ok, I have a list of points from two different polyline objects. I need to compare to see if the list points are identical, but I need to account for the fact that the order of the points may be different. Any ideas on how to accomplish this?

[Tharwat]

Try this .
lst-1 represents the first list as well the second one .

Code - Auto/Visual Lisp: [Select]

1. (vl-every '(lambda (q p) (equal q p 1e-8)) lst-1 lst-2)
2.  

[cmwade77]

Perhaps I am doing something wrong, here is what I have:

Code: [Select]

(setq PtA (vlax-safearray->list (vlax-variant-value retCoordA))
PtB (vlax-safearray->list (vlax-variant-value retCoordB))
)
(if (vl-every '(lambda (q p) (equal q p 1e-8)) PtA PtB)
     (alert "Objects are the same")
     (alert "Objects are different")
)
Even when the objects are the same, it returns that they are different.

[ribarm]

Code - Auto/Visual Lisp: [Select]

1. (vl-every '(lambda ( x ) (eq x T)) (mapcar '(lambda ( x ) (vl-some '(lambda ( y ) (equal x y 1e-5)) lst-1)) lst-2))
2.  

The same as Tharwat explained lst-1 and lst-2 are point lists...

[Tharwat]

Post the two lists PtA and PtB to have a close look .

[cmwade77]

Ok, here are the list of points:
PtA - (9.34785 4.79562 9.34785 5.55109 10.2356 5.55109 10.2356 4.79562)
PtB - (9.34785 5.55109 9.34785 4.79562 10.2356 5.55109 10.2356 4.79562)

[ribarm]

Code: [Select]

Command: (setq lst-1 '(9.34785 4.79562 9.34785 5.55109 10.2356 5.55109 10.2356
4.79562))
(9.34785 4.79562 9.34785 5.55109 10.2356 5.55109 10.2356 4.79562)

Command: (setq lst-2 '(9.34785 5.55109 9.34785 4.79562 10.2356 5.55109 10.2356
4.79562))
(9.34785 5.55109 9.34785 4.79562 10.2356 5.55109 10.2356 4.79562)

Command: (vl-every '(lambda ( x ) (eq x T)) (mapcar '(lambda ( x ) (vl-some
'(lambda ( y ) (equal x y 1e-5)) lst-1)) lst-2))
T

Command: (vl-every '(lambda (q p) (equal q p 1e-8)) lst-1 lst-2)
nil

My and Tharwat's codes...
HTH

[Lee Mac]

Code - Auto/Visual Lisp: [Select]

1. (vl-every '(lambda ( x ) (eq x T)) (mapcar '(lambda ( x ) (vl-some '(lambda ( y ) (equal x y 1e-5)) lst-1)) lst-2))
2.  

The same as Tharwat explained lst-1 and lst-2 are point lists...

This can be reduced to:

Code - Auto/Visual Lisp: [Select]

1. (vl-every '(lambda ( x ) (vl-some '(lambda ( y ) (equal x y 1e-8)) PtB)) PtA)

[Lee Mac]

Or recursively,

Code - Auto/Visual Lisp: [Select]

1. (defun f ( l1 l2 )
2.     (or (null l1) (and (g (car l1) l2) (f (cdr l1) l2)))
3. )
4. (defun g ( x l )
5.     (and l (or (equal x (car l) 1e-8) (g x (cdr l))))
6. )

Code - Auto/Visual Lisp: [Select]

1. (f PtA PtB)

[roy_043]

... to see if the list points are identical...

Do you want to check if the polylines overlap? If so, the order of the points is still important. Also the OCS and the elevation should be taken into account.

[Patrick_35]

Hi

To compare two list without vl-every

Code: [Select]

(setq lst-1 '(9.34785 4.79562 9.34785 5.55109 10.2356 5.55109 10.2356 4.79562))
(setq lst-2 '(9.34786 4.79563 9.34786 5.55110 10.2357 5.55110 10.2357 4.79563))
(equal lst-1 lst-2 1e-4) --> T
(equal lst-1 lst-2 1e-5) --> nil

@+

[Kerry]

Hi

To compare two list without vl-every

< ... >


(equal lst-1 lst-2 1e-4) --> T
(equal lst-1 lst-2 1e-5) --> nil

[cmwade77]

Hi

To compare two list without vl-every

< ... >


(equal lst-1 lst-2 1e-4) --> T
(equal lst-1 lst-2 1e-5) --> nil

This only seems to work if the order is identical.

[Kerry]

< .. >
This only seems to work if the order is identical.

Yes,
I tried to visualise the use for comparing point lists where the point order does not matter.
.... wasn't successful.
Care to share the purpose of the test ?

[roy_043]

... to see if the list points are identical...

Do you want to check if the polylines overlap? If so, the order of the points is still important. Also the OCS and the elevation should be taken into account.