Re: How to improve my summarizing code

On 6/23/2024, B. Pym wrote:

(defun summarize (list)
   (loop with summary = nil
         for elt in list
         for sum = (find (first elt) summary :test #'eql :key #'first)
         if sum do (incf (second sum) (second elt))
         else do (push elt summary)
         finally (return summary)))
 
CL-USER 2 > (summarize '((c 7) (a 1) (a 3) (b 1) (b 10) (b 100)))
((B 111) (A 4) (C 7))

(define (summarize alist)
  (let1 keys (delete-duplicates (map car alist))
    (map
      (lambda(k)
        (list k
          (apply +
            (filter-map
              (lambda(x) (and (equal? k (car x)) (cadr x)))
              alist))))
      keys)))

(summarize '((c 7) (a 1) (a 3) (b 1) (b 10) (b 100)))
  ===>
((c 7) (a 4) (b 111))