Re: performance of converting alist to hash table

[Dai Yuwen <daiyuwen@sdf.lonestar.org>]

On Sun, May 16, 2004 at 01:18:07PM +0200, Eli Zaretskii wrote:
> > Date: Sun, 16 May 2004 09:55:22 +0000
> > From: Dai Yuwen <daiyuwen@sdf.lonestar.org>
> > 
> > I'm trying to convert a large alist(nearly 7000 elements in it) to a
> > hash table. But I found the performence of my function is poor: on a
> > Celeron 333MHz, 196M memory system, it'll take 15 seconds to finish
> > converting. 
> > 
> > This is the function:
> > 
> > (defun convert-alist-to-hash (table  w)
> >   (let ((l w))
> >      (while l
> >        (setq char (car (car l))
> >              key (car (cdr (car l)))
> >              l (cdr l))
> >        (puthash char key table))))
> 
> Did you try `mapcar' and its variants?
> 
I use `mapc' like this:
(defun convert-alist-to-hash (table  w)
  (mapc (lambda (e)
          (puthash (car e) (cadr e) table))
        w))

Almost the same time needed. (I made a mistake in the previous email, it should be 30 seconds instead of 15.) 

best regards,
Dai Yuwen

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