Topic: list question

[ElpanovEvgeniy]

>CAB
It is a lot of work and not enough free time...

[ElpanovEvgeniy]

Has forgotten to explain...
(equal 0. (area-polygon lst) 0.01)
0.01 = (sqrt 1e-4)

[ElpanovEvgeniy]

Code: [Select]

(defun test-2.1 (lst)
 (equal
  0.
  (apply (function +)
         (mapcar (function (lambda (a b)
                            (+ (* (+ (car a) (car b)) (- (cadr a) (cadr b)))
                               (* (+ (cadr a) (cadr b)) (- (caddr a) (caddr b)))
                               (* (+ (caddr a) (caddr b)) (- (car a) (car b)))
                            ) ;_  +
                           ) ;_  lambda
                 ) ;_  function
                 (cons (last lst) lst)
                 lst
         ) ;_  mapcar
  ) ;_  apply
  0.01
 ) ;_  equal
) ;_  defun

[gile]

Joe,

I think the way I gave works because proportinality is a linear function.

But here's another purpose, asumming lst is a list of pairs ((minpt1 maxpt1) (minpt2 maxpt2) ... (minptn maxptn)).
If each bounding box is proportionnal, each of their their diagonals are parallel.

Code: [Select]

(defun test (lst)
  (vl-every
    '(lambda (pair)
       (null (inters (caar lst) (cadar lst) (car pair) (cadr pair))
       )
     )
    (cdr lst)
  )
)

Hi, Evgeniy, glad to read you again

[CAB]

Hard to forget a Giant. 

[ElpanovEvgeniy]

The version with use of a vector of a normal...

Code: [Select]

(defun v_norm_2v (v1 v2)
 ;; By ElpanovEvgeniy
 ;; Vector normal
 ((lambda (a b)
   (mapcar (function (lambda (a1 b1 a2 b2) (- (* a1 b1) (* a2 b2)))) a (cdr b) b (cdr a))
  ) ;_  lambda
  (list (cadr v1) (caddr v1) (car v1) (cadr v1))
  (list (cadr v2) (caddr v2) (car v2) (cadr v2))
 ) ;_  lambda
) ;_  defun
(defun test-3 (lst)
 (vl-every '(lambda (x) (equal 0. x 0.01))
           (apply 'append (mapcar 'v_norm_2v lst (cdr lst)))
 ) ;_  vl-every
) ;_  defun

[Joe Burke]

Joe,

I think the way I gave works because proportinality is a linear function.

But here's another purpose, asumming lst is a list of pairs ((minpt1 maxpt1) (minpt2 maxpt2) ... (minptn maxptn)).
If each bounding box is proportionnal, each of their their diagonals are parallel.

Code: [Select]

(defun test (lst)
  (vl-every
    '(lambda (pair)
       (null (inters (caar lst) (cadar lst) (car pair) (cadr pair))
       )
     )
    (cdr lst)
  )
)

Hi, Evgeniy, glad to read you again

gile,

That looks like a perfect solution!

Of course I'm wondering why I didn't see it.

I think there is a need for a fuzz factor. I'll have to study Evgeniy's code, which seems to allow that.

Thanks guys.

[Joe Burke]

Perhaps I don't understand, but if you are testing a group of bounding boxes for ratios could
you compare the width to height ratios?
(setq ratio (/ (distance p1 p2) (distance p2 p3)))

Alan,

Yes, that might be another way to aproach the issue.

Thanks

[ElpanovEvgeniy]

gile,

That looks like a perfect solution!

Of course I'm wondering why I didn't see it.

I completely agree. This best decision from all shown.
My decisions, only show other ideas...

Code: [Select]

(defun area_triangle_geron (d1 d2 d3 / d)
 ;; By ElpanovEvgeniy
 ;; area triangle, Geron
 (setq d (* (+ d1 d2 d3) 0.5))
 (sqrt (abs (* d (- d d1) (- d d2) (- d d3))))
)
(defun test-4 (lst)
 (vl-every
  '(lambda (a) (equal a 0. 0.01))
  (mapcar
   '(lambda (a b c) (area_triangle_geron (distance a b) (distance a c) (distance b c)))
   (cons (last lst) lst)
   lst
   (reverse (cons (car lst) (reverse (cdr lst))))
  ) ;_  mapcar
 ) ;_  vl-every
) ;_  defun

[ElpanovEvgeniy]

The version with use of a vector of a normal...

Code: [Select]

(defun v_norm_2v (v1 v2)
 ;; By ElpanovEvgeniy
 ;; Vector normal
 ((lambda (a b)
   (mapcar (function (lambda (a1 b1 a2 b2) (- (* a1 b1) (* a2 b2)))) a (cdr b) b (cdr a))
  ) ;_  lambda
  (list (cadr v1) (caddr v1) (car v1) (cadr v1))
  (list (cadr v2) (caddr v2) (car v2) (cadr v2))
 ) ;_  lambda
) ;_  defun
(defun test-3 (lst)
 (vl-every '(lambda (x) (equal 0. x 0.01))
           (apply 'append (mapcar 'v_norm_2v lst (cdr lst)))
 ) ;_  vl-every
) ;_  defun

This version approaches only for the list of vectors... 
If it to use for the list of the points laying on an any straight line it is necessary to make changes and to result all points in a vector!

Code: [Select]

(defun test-3.1 (lst)
 (vl-every '(lambda (x) (equal 0. x 0.01))
           (apply 'append
                  ((lambda (lst) (mapcar 'v_norm_2v lst (cdr lst)))
                   (mapcar '(lambda (a b) (mapcar '- a b)) lst (cdr lst))
                  )
           ) ;_  apply
 ) ;_  vl-every
) ;_  defun

[gile]

gile,

That looks like a perfect solution!

First, thanks.

But I think it's not really perfect.
It will work if all points are in the same plane but ((0 0 0) (1 1 0)) and ((0 1 1) (1 0 1)) have no intersection but aren't parallel.

Another purpose using single unit vectors, more, this one allows a fuzz.

Always with a list of pairs like ((minpt1 maxpt1) (minpt2 maxpt2) ... (minptn maxptn))

Code: [Select]

;;; VEC1 Returns the single unit vector from p1 to p2

(defun vec1 (p1 p2 / d)
  (if (not (zerop (setq d (distance p1 p2))))
    (mapcar '(lambda (x1 x2) (/ (- x2 x1) d)) p1 p2)
  )
)

(defun test (lst / vec)
  (and
    (setq vec (vec1 (caar lst) (cadar lst)))
    (vl-every
      '(lambda (pair)
(equal vec (vec1 (car pair) (cadr pair)) 1e-9)
       )
      (cdr lst)
    )
  )
)

[Joe Burke]

Thanks gile and Evgeniy.