Re: Any way to collect all the values of a hash table more concisely ?

Leandro Rios wrote:

Leandro Rios escribió:
 

So this new version works as intended:

 

(defun cluster-by (fn list &aux (clusters (make-hash-table)) (result nil))
    (mapcar #'(lambda (x) (push x (gethash (funcall fn x) clusters))) list)
    (maphash  #'(lambda (key value) (push value result)) clusters)
    (sort result #'< :key #'(lambda (x) (length (car x)))))

 
Um, sorry:
 
(defun cluster-by (fn list &aux (clusters (make-hash-table)) (result nil))
     (mapcar #'(lambda (x) (push x (gethash (funcall fn x) clusters))) list)
     (maphash  #'(lambda (key value) (push value result)) clusters)
     (sort result #'< :key #'(lambda (x) (funcall fn (car x)))))
                                          ^^^^^^^^^^

newLISP

(macro (aalt! Alist Key Func Default)
  (if (assoc Key Alist)
    (setf (assoc Key Alist) (list ($it 0) (Func ($it 1))))
    (push (list Key (Func Default)) Alist)))

(macro (apush! Alist Key Val)
  (aalt! Alist Key (curry cons Val) '()))

(define (group-by func lst   (alist '()))
  (dolist (x lst) (apush! alist (func x) x))
  alist)

(group-by length '("a" "b" "abc" "bc" "a" "abcd" "e" "fg"))
  ===>
((4 ("abcd")) (2 ("fg" "bc")) (3 ("abc")) (1 ("e" "a" "b" "a")))