Topic: iteration code : short and efficiency challenge

[Kerry]

i cant test it right now but looking at the code cant really  understand why you put s in a list?

What does the function return ... which variable ??



what is the result of this

Code - Auto/Visual Lisp: [Select]

1. (setq startpoint '(1 1 1) )

Then:

Code - Auto/Visual Lisp: [Select]

1. (setq result (list startpoint))

Then :

Code - Auto/Visual Lisp: [Select]

1. (setq result (cons '(2 2 2) result))

[Kerry]

< ..>

no i dont , but i read about it, i assume its this

Code: [Select]

(defun isCoordReal (crd)
  (car
    (mapcar
      (function
(lambda (x y z)
  (= (type x) 'REAL)
  (= (type y) 'REAL)
  (= (type z) 'REAL)
  )
)
      (list (car crd))
      (list (cadr crd))
      (list (caddr crd))
      )
    )
  )


i cant understand why but the returned value is a list (T)  rather than an element. the car exp is totally ignored.

Perhaps have a play with something like this as an alternative :

Code - Auto/Visual Lisp: [Select]

1. (defun point-p (pt )
2.   (and (listp pt) (= 3 (vl-list-length pt)) (vl-every 'numberp pt))
3.  
4. )

edit kdub: revised from (vl-member-if 'numberp pt)to(vl-every 'numberp pt)

[Shay Gaghe]

i cant test it right now but looking at the code cant really  understand why you put s in a list?

What does the function return ... which variable ??



what is the result of this

Code - Auto/Visual Lisp: [Select]

1. (setq startpoint '(1 1 1) )

Then:

Code - Auto/Visual Lisp: [Select]

1. (setq result (list startpoint))

Then :

Code - Auto/Visual Lisp: [Select]

1. (setq result (cons '(2 2 2) result))

I get it now
Thank you Kerry

[Shay Gaghe]

< ..>

no i dont , but i read about it, i assume its this

Code: [Select]

(defun isCoordReal (crd)
  (car
    (mapcar
      (function
(lambda (x y z)
  (= (type x) 'REAL)
  (= (type y) 'REAL)
  (= (type z) 'REAL)
  )
)
      (list (car crd))
      (list (cadr crd))
      (list (caddr crd))
      )
    )
  )


i cant understand why but the returned value is a list (T)  rather than an element. the car exp is totally ignored.

Perhaps have a play with something like this as an alternative :

Code - Auto/Visual Lisp: [Select]

1. (defun point-p (pt )
2.   (and (listp pt) (= 3 (vl-list-length pt)) (vl-member-if 'numberp pt))
3. )

i didnt know about numbrtp function.  Thanx

anyhow i would be happy to understand why my writen function return a list and not an atom as it were instructed to do.

[roy_043]

Perhaps have a play with something like this as an alternative :

Code - Auto/Visual Lisp: [Select]

1. (defun point-p (pt )
2.   (and (listp pt) (= 3 (vl-list-length pt)) (vl-member-if 'numberp pt))
3. )

Not doubt you meant to use vl-every instead of vl-member-if:

Code: [Select]

(point-p '(1 "a" 3)) => T

[roy_043]

anyhow i would be happy to understand why my writen function return a list and not an atom as it were instructed to do.

But your function does not return a list! It is flawed though:

Code: [Select]

(isCoordReal '(1.0 "a" 3.0)) => T

[Kerry]

Perhaps have a play with something like this as an alternative :

Code - Auto/Visual Lisp: [Select]

1. (defun point-p (pt )
2.   (and (listp pt) (= 3 (vl-list-length pt)) (vl-member-if 'numberp pt))
3. )

Not doubt you meant to use vl-every instead of vl-member-if:

Code: [Select]

(point-p '(1 "a" 3)) => T

Thanks Roy ,

I'm rushing too much ..   

Code revised.

[bruno_vdh]

Hi,

wow....its too advanced for me. can you please give a simple code which explain better how to design recursive functions?

Perhaps this version it will be easier for you ...

Code: [Select]

(defun f (s i n)
  (if (> n 0)
    (cons s (f (mapcar '+ s i) i (1- n)))
  )
)
Or

Code: [Select]

(defun f (s i n)
  (if (> n 1)
    (cons s (f (mapcar '+ s i) i (1- n)))
    (list s)
  )
)


Code: [Select]

_$ (f '(1 2 42) '(5 0 0) 5)
((1 2 42) (6 2 42) (11 2 42) (16 2 42) (21 2 42))

One more not keep the starting point in the outcome.

Code: [Select]

(defun f (s i n)
  (if (> n 0)
    (cons (setq s (mapcar '+ s i)) (f s i (1- n)))
  )
)


Code: [Select]

_$ (f '(1 2 42) '(5 0 0) 4)
((6 2 42) (11 2 42) (16 2 42) (21 2 42))


no i dont , but i read about it, i assume its this

Code: [Select]

(defun isCoordReal (crd)
  (car
    (mapcar
      (function
(lambda (x y z)
  (= (type x) 'REAL)
  (= (type y) 'REAL)
  (= (type z) 'REAL)
  )
)
      (list (car crd))
      (list (cadr crd))
      (list (caddr crd))
      )
    )
  )

i cant understand why but the returned value is a list (T)  rather than an element. the car exp is totally ignored.

My variant:

Code: [Select]

(defun 3Dpoint-p (pt)
  (and (numberp (car pt)) (numberp (cadr pt)) (numberp (caddr pt)) (null (cdddr pt)))
)

Best Regards

[Shay Gaghe]

This should offer some minor performance improvements:

Code - Auto/Visual Lisp: [Select]

1. (defun measure1 ( s e i / a r )
2.     (setq r (list s)
3.           a (angle s e)
4.     )
5.     (repeat (fix (/ (distance s e) i))
6.         (setq r (cons (polar (car r) a i) r))
7.     )
8. )

A genius is a person who displays exceptionally superior intellectual ability, creativity, or originality, typically to a degree that is associated with the achievement of new advances in a domain of knowledge. A scholar in many subjects or a scholar in a single subject may be referred to as a genius.[1] There is no scientifically precise definition of genius, and the question of whether the notion itself has any real meaning has long been a subject of debate, although psychologists are converging on a definition that emphasizes creativity and eminent achievement.

[Shay Gaghe]

hi

i need mapcar to iterate each 2 items rather than each item. i sign it with this code

Code: [Select]

(defun mapcar-x2(lst)
  (mapcar
    (function
      (lambda (a b)
(command "._line" a b)
(princ (strcat "Segment length: " (distance a b) ))
      )
     )
    lst ;_ how to shuffle the list in a way a and b will have not the same number each iteration?
   lst
    )
  )

hope i am unmderstood
Thanks
Shay

[VovKa]

use (cdr lst) as a second argument

[Shay Gaghe]

im not sure i get what you say

[VovKa]

Code: [Select]

(mapcar (function (lambda (a b)
    .....
  )
)
lst
(cdr lst)
)


[Shay Gaghe]

Code: [Select]

(defun mapcar-x2(lst)
  (mapcar
    (function
      (lambda (a b)

(princ (strcat "Segment length: " (distance a b) ))
      )
     )
    lst
    (cdr lst)
    )
  )



Code: [Select]

_$ (mapcar-x2 '( (0 0 0)(0 0 0)(0 0 0)(0 0 0)) )

Code: [Select]

; error: bad argument type: stringp 0.0

[ElpanovEvgeniy]

Hi Evgeniy,

Nice bit of code.

I think   (f (list 1 2 42) '(5 2 0) 4)

should return  ( (21 10 42) (16 8 42) (11 6 42) (6 4 42) )

Regards,

Thanks!
I understood, but not immediately...