Re: Partition for Emacs Lisp

[Pascal J. Bourguignon]

Marc Tfardy <bum@cyk.cyk> writes:

> Hi!
>
> I looking for a ELISP function that do the job like Partition in
> Mathematica. The simplest case:
>
> (partition '(a b c d e f) 2)
> should return:
> ((a b) (c d) (e f))

(defun partition-list (list length)
  (loop
     while list
     collect (subseq list 0 length)
     do (setf list (nthcdr length list))))

(defun partition-vector (vector length)
  (loop
     for i = 0 then (+ i length)
     while (< i (length vector))
     collect (subseq vector i (+ i length))))
     
(defun partition (sequence length)
   (etypecase sequence
      (list   (partition-list sequence length))
      (string (partition-vector sequence length)) ; emacs lisp strings are not 
vectors! 
      (vector (partition-vector sequence length))))

(partition '[a b c d e f] 2)  -> ([a b] [c d] [e f])
(partition '(a b c d e f) 2)  -> ((a b) (c d) (e f))
(partition '"abcdef" 2)       -> ("ab" "cd" "ef")


> Is there something ready out from the box?

Perhaps.  But if you didn't search in the manual, it must be because
it would take more time than to write partition yourself, so I didn't
search in the manual either, and wrote it to steal you the fun of
writing it yourself.


-- 
__Pascal Bourguignon__