Counting the occurrences of unique atoms

DFLY · January 2023

Hello
Is there a better way to count the occurrences of unique atoms in a list ?
Here is my code:

(defun c:fff()                ;fff is just easy to press on a keyboard.
  (setq aa '(1 1 1 2 2 2 2 3 3 3 3 3)) ; The test set of atoms
  (setq bb '())             ;A secondary list to hold aa again for iterating throuh
  (setq cc '())              ;This will be the dotted pair of atom and its count
  (setq dd '())              ;The final list of all atoms and their counts
  (setq ee '())               ;Just one of each unique atom and its count
  (setq bb (append aa bb)) ;load aa int bb
	
  (foreach xx aa
      (setq ctr 0) ; A counter used to count the quantity of eacy uniuqe atom occurance
      (foreach yy bb ;compare each item in aa to all of the items from aa copied to bb 
                     ;and move the counter up each time  one occurs
         (if (= xx yy)
						
            (setq ctr (1+ ctr))
							
							
         )
      )
   (setq cc (cons xx ctr)) ;create dotted pare of each atom and its number of occurances
   (setq dd (cons cc dd)) ;pass the dotted pairs to a list
   )
	
 (foreach xx aa
    (if (not (assoc xx ee)) ;only add the pairs form dd to ee if thay are not already in ee
        (setq ee (cons (assoc xx dd) ee))
			
     )
  )
(print "ee") (print ee) (princ)
)

I don't know many of the vl codes, so perhaps it is possible to do this with just one function ?

DFLY · January 2023

DFLY said:
Hello
Is there a better way to count the occurrences of unique atoms in a list ?
Here is my code:
(defun c:fff() ;fff is just easy to press on a keyboard. (setq aa '(1 1 1 2 2 2 2 3 3 3 3 3)) ; The test set of atoms (setq bb '()) ;A secondary list to hold aa again for iterating throuh (setq cc '()) ;This will be the dotted pair of atom and its count (setq dd '()) ;The final list of all atoms and their counts (setq ee '()) ;Just one of each unique atom and its count (setq bb (append aa bb)) ;load aa int bb (foreach xx aa (setq ctr 0) ; A counter used to count the quantity of eacy uniuqe atom occurance (foreach yy bb ;compare each item in aa to all of the items from aa copied to bb ;and move the counter up each time one occurs (if (= xx yy) (setq ctr (1+ ctr)) ) ) (setq cc (cons xx ctr)) ;create dotted pare of each atom and its number of occurances (setq dd (cons cc dd)) ;pass the dotted pairs to a list ) (foreach xx aa (if (not (assoc xx ee)) ;only add the pairs form dd to ee if thay are not already in ee (setq ee (cons (assoc xx dd) ee)) ) ) (print "ee") (print ee) (princ) )

I don't know many of the vl codes, so perhaps it is possible to do this with just one function ?

Sorry about the weird format. The code format did that. Here it is again

(defun c:fff() ;fff is just easy to press on a keyboard.
(setq aa '(1 1 1 2 2 2 2 3 3 3 3 3)) ; The test set of atoms
(setq bb '()) ;A secondary list to hold aa again for iterating throuh
(setq cc '()) ;This will be the dotted pair of atom and its count
(setq dd '()) ;The final list of all atoms and their counts
(setq ee '()) ;Just one of each unique atom and its count
(setq bb (append aa bb)) ;load aa int bb

(foreach xx aa
(setq ctr 0) ; A counter used to count the quantity of eacy uniuqe atom occurance
(foreach yy bb ;compare each item in aa to all of the items from aa copied to bb
;and move the counter up each time one occurs
(if (= xx yy)

(setq ctr (1+ ctr))

)
)
(setq cc (cons xx ctr)) ;create dotted pare of each atom and its number of occurances
(setq dd (cons cc dd)) ;pass the dotted pairs to a list
)

(foreach xx aa
(if (not (assoc xx ee)) ;only add the pairs form dd to ee if thay are not already in ee
(setq ee (cons (assoc xx dd) ee))

)
)
(print "ee") (print ee) (princ)
)

Roy Klein Gebbinck · January 2023

; (count_atoms '(1 1 1 2 2 2 2 3 3 3 3 3))
(defun count_atoms (lst / fnd res)
  (foreach itm lst
    (if (setq fnd (assoc itm res))
      (setq res (subst (cons itm (1+ (cdr fnd))) fnd res))
      (setq res (cons (cons itm 1) res))
    )
  )
  (reverse res)
)

DFLY · January 2023

Roy Klein Gebbinck said:

; (count_atoms '(1 1 1 2 2 2 2 3 3 3 3 3))
(defun count_atoms (lst / fnd res)
  (foreach itm lst
    (if (setq fnd (assoc itm res))
      (setq res (subst (cons itm (1+ (cdr fnd))) fnd res))
      (setq res (cons (cons itm 1) res))
    )
  )
  (reverse res)
)

Wow! Thanks. So much to digest from such a small script. I didn't know I could cons an atom with nil.

Roy Klein Gebbinck · January 2023

Nil is special. It is both an atom and an empty list:

(atom nil) => T
(listp nil) => T
(= nil '()) => T

Counting the occurrences of unique atoms

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