How to make elements of several lists into one in lisp

Question

I'm trying to take a list of lists of lists (don't worry, I'll put an example) and convert the elements of each last least into one. This is what I've done so far:

(defun cost(state)
(let ((list_elements '()))
(dolist (element state)
  (dolist (subElement element)
    (setq list_elements (append list_elements (list subElement))))
finally (return list_elements))))

Example:

(list
(list
    (list
        (list 1 9 't121) 
        (list 1 10 't122))
    (list
        (list 2 10 't123)
        (list 2 11 't124)))
(list
    (list
        (list 1 9 't121)
        (list 1 11 't132))
    (list
        (list 2 11 't133)
        (list 2 12 't134))))

So, this is supposed to return ((1 9 T121) (1 10 T122) (2 10 T123) (2 11 T124) (1 9 T121) (1 11 T132) (1 11 T132) (2 11 T133) (2 12 T134)) And it is only returning ((1 9 T121) (1 11 T132))

After that, I'm supposed to count the number of different elements in the list.

Does anyone see what the problem is in this function?

score 1 · Accepted Answer · 2012-11-28 17:47:49Z

1

(defun double-append (list)
  (reduce #'append (reduce #'append list)))

;; or like this:
(defun mapcan-mapcon (list)
  (mapcan #'append (mapcon #'car list)))

(double-append (list
 (list
  (list
   (list 1 9 't121) 
   (list 1 10 't122))
  (list
   (list 2 10 't123)
   (list 2 11 't124)))
 (list
  (list
   (list 1 9 't121)
   (list 1 11 't132))
  (list
   (list 2 11 't133)
   (list 2 12 't134)))))

((1 9 T121) (1 10 T122) (2 10 T123) (2 11 T124) (1 9 T121) (1 11 T132)
 (2 11 T133) (2 12 T134))

So far I could tell by the expected result, that must be something like it.

;; Using Alexandria, just as an example, of how currying can save
;; some repetitive coding:
(ql:quickload "alexandria")
(defun curried-append ()
  (let ((reducer (alexandria:curry #'reduce #'append)))
    (alexandria:compose reducer reducer)))

(funcall
 (curried-append)
 (list
  (list
   (list
    (list 1 9 't121) 
    (list 1 10 't122))
   (list
    (list 2 10 't123)
    (list 2 11 't124)))
  (list
   (list
    (list 1 9 't121)
    (list 1 11 't132))
   (list
    (list 2 11 't133)
    (list 2 12 't134)))))

edited Nov 28, 2012 at 17:47

answered Nov 28, 2012 at 17:23

user797257

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3 Comments

FriedRike Over a year ago

That's almost it. That functions returns this: (1 9 T121 1 11 T132 2 11 T133 2 12 T134 3 11 T111 3 10 T001) but that's ok, found the solution

FriedRike Over a year ago

Do you know how I can find the number of different elements in a list?

FriedRike Over a year ago

I asked Google, and for the first time in my life, he didn't know the answer (or didn't want to show it o me)

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