Topic: List Functions

[snownut2]

Time for some additional basic List Functions;
       ListSum = Sum of all numbers in a numbered list
       ListMax = Largest number contained in a numbered list
       ListMin  = Smallest "                                                      "

I'm sure there are tons more !!

[ribarm]

Code - Auto/Visual Lisp: [Select]

1. (defun ListSum ( lst / x xx )
2.   (setq xx 0)
3.   (while lst
4.     (setq x (car lst))
5.     (setq xx (+ x xx))
6.     (setq lst (cdr lst))
7.   )
8.   xx
9. )
10.  
11. (defun ListMax ( lst / x xx )
12.   (while lst
13.     (setq x (car lst))
14.     (setq xx (cond (xx) ((cadr lst))))
15.     (setq xx (max x xx))
16.     (setq lst (cdr lst))
17.   )
18.   xx
19. )
20.  
21. (defun ListMin ( lst / x xx )
22.   (while lst
23.     (setq x (car lst))
24.     (setq xx (cond (xx) ((cadr lst))))
25.     (setq xx (min x xx))
26.     (setq lst (cdr lst))
27.   )
28.   xx
29. )
30.  

[CAB]

Code: [Select]

(defun ListSum ( lst)
 (apply '+ lst)
)
 
(defun ListMax ( lst / x xx )
 (apply 'max lst)
)
 
(defun ListMin ( lst / x xx )
 (apply 'min lst)
)

[snownut2]

Code: [Select]

(defun ListSum ( lst)
 (apply '+ lst)
)
 
(defun ListMax ( lst / x xx )
 (apply 'max lst)
)
 
(defun ListMin ( lst / x xx )
 (apply 'min lst)
)

Thanks CAB, I'm not that familiar with the apply function.  This is a good example though.

Bruce

[Tharwat]

CAB , you have localized variables that are not needed .

[Lee Mac]

I'm not that familiar with the apply function.

If you have an aversion to the apply function:

Code - Auto/Visual Lisp: [Select]

1. (defun listsum ( l ) (eval (cons '+ l)))
2. (defun listmin ( l ) (eval (cons 'min l)))
3. (defun listmax ( l ) (eval (cons 'max l)))

[Lee Mac]

Or, if you wanted to iterate over the lists...

Code - Auto/Visual Lisp: [Select]

1. (defun listsum ( l / r )
2.     (setq r 0)
3.     (foreach x l (setq r (+ x r)))
4.     r
5. )
6. (defun listmin ( l / r )
7.     (setq r (car l))
8.     (foreach x (cdr l) (setq r (min r x)))
9.     r
10. )
11. (defun listmax ( l / r )
12.     (setq r (car l))
13.     (foreach x (cdr l) (setq r (max r x)))
14.     r
15. )

[CAB]

CAB , you have localized variables that are not needed .

Yes, I was being lazy, copy & paste from previous post.

[snownut2]

Lee, for the "SUM" result your last post is exactly how I had accomplished it, for the MIN/MAX I had sorted the list </> then selected the 1st element.  I was not real keen on the sort idea.

Thanks guys for the quick response's

Bruce

[Lee Mac]

I was not real keen on the sort idea.

Yes - sorting all items in the list is very inefficient if you are only interested in the min/max 

[David Bethel]

Maybe flush out the functions :

Code: [Select]

;;;Product of a list
  (defun ListProd (l)
    (apply '* l))

;;;Mean or Average of a list
  (defun ListAvg (l)
    (/ (apply '+ l) (float (length l))))

;;;Median of a SORTED list
  (defun ListMed (l / c)
    (setq c (length l))
    (if (= (rem c 2) 1)
        (nth (fix (/ c 2.0)) l)
        (/ (+ (nth (1- (fix (/ c 2.0))) l)
              (nth (fix (/ c 2.0)) l))
           2.0)))

;;;Range of a list
  (defun ListRng (l / c)
    (- (apply 'max l)
       (apply 'min l)))

;;;Mode of a list
  (defun ListMode (l / c r x m)
    (setq c nil)
    (foreach a l
      (setq c (if (assoc a c)
                  (subst (list a (1+ (cadr (assoc a c))))
                         (assoc a c) c)
                  (cons (list a 1) c))))
    (setq r (mapcar ' reverse c)
          x (apply 'max (mapcar 'car r)))
    (cond ((= x 1) (setq m "None"))
          (T
           (foreach a r
             (if (= (car a) x)
                 (setq m (cons (cadr a) m))))))
    m)


Prime Factors & Least Common Multiple would be cool

-David

[Lee Mac]

Another for mode:

http://www.theswamp.org/index.php?topic=45195.msg503882#msg503882

[Lee Mac]

Least Common Multiple would be cool

A possible candidate for LCM:

Code - Auto/Visual Lisp: [Select]

1. (defun lcm ( l / f )
2.     (defun f ( a b / m )
3.         (if (apply '= a)
4.             (car a)
5.             (progn
6.                 (setq m (apply 'min a))
7.                 (f (mapcar '(lambda ( a b ) (if (= a m) (+ a b) a)) a b) b)
8.             )
9.         )
10.     )
11.     (f l l)
12. )

Code - Auto/Visual Lisp: [Select]

1. _$ (lcm '(22 16 31))
2. 5456

[Lee Mac]

Another:

Code - Auto/Visual Lisp: [Select]

1. (defun lcm ( l )
2.     (/ (apply '* l) (apply '* (mapcar 'gcd l (cdr l))))
3. )

[David Bethel]

Another:

Code - Auto/Visual Lisp: [Select]

1. (defun lcm ( l )
2.     (/ (apply '* l) (apply '* (mapcar 'gcd l (cdr l))))
3. )

That'a a good 1 !


PS

On second look, I don't think this 1 works

Code: [Select]

  (setq lst '(2 5 5 5 6 7 10 10 10 12))
  (lcm lst)
  25200