From: Ted Zlatanov <tzz@lifelogs.com>
To: help-gnu-emacs@gnu.org
Subject: Re: random predicate function
Date: Mon, 13 Dec 2010 11:16:21 -0600 [thread overview]
Message-ID: <87r5dlmw4a.fsf@lifelogs.com> (raw)
In-Reply-To: 87mxo9r8xg.fsf@kuiper.lan.informatimago.com
On Mon, 13 Dec 2010 16:26:03 +0100 "Pascal J. Bourguignon" <pjb@informatimago.com> wrote:
PJB> You could instead put your paragraphs in a vector and use:
PJB> (defun shuffle (vector)
PJB> "Re-orders randomly the vector."
PJB> (loop
PJB> for i from (1- (length vector)) downto 1
PJB> do (rotatef (aref vector i) (aref vector (random i)))))
PJB> to shuffle them and then re-insert them.
I noticed this function in lisp/play/cookie1.el which doesn't require
CL:
; Thanks to Ian G Batten <BattenIG@CS.BHAM.AC.UK>
; [of the University of Birmingham Computer Science Department]
; for the iterative version of this shuffle.
;
;;;###autoload
(defun shuffle-vector (vector)
"Randomly permute the elements of VECTOR (all permutations equally likely)."
(let ((i 0)
j
temp
(len (length vector)))
(while (< i len)
(setq j (+ i (random (- len i))))
(setq temp (aref vector i))
(aset vector i (aref vector j))
(aset vector j temp)
(setq i (1+ i))))
vector)
I wonder if it should be moved out of cookie1.el.
Ted
next prev parent reply other threads:[~2010-12-13 17:16 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.0.1292251427.11097.help-gnu-emacs@gnu.org>
2010-12-13 15:26 ` random predicate function Pascal J. Bourguignon
2010-12-13 17:16 ` Ted Zlatanov [this message]
2010-12-13 17:48 ` Pascal J. Bourguignon
2010-12-15 14:51 ` Ted Zlatanov
2010-12-15 15:20 ` Pascal J. Bourguignon
2010-12-15 16:44 ` Ted Zlatanov
2010-12-15 17:28 ` Pascal J. Bourguignon
2010-12-15 18:39 ` Ted Zlatanov
2010-12-15 18:04 ` Drew Adams
2010-12-13 18:17 ` Tyler Smith
[not found] ` <mailman.2.1292264248.1009.help-gnu-emacs@gnu.org>
2010-12-13 18:38 ` Pascal J. Bourguignon
2010-12-13 19:05 ` Tyler Smith
2010-12-13 14:43 Tyler Smith
2010-12-13 15:37 ` Gary
2010-12-13 16:08 ` Tyler Smith
2010-12-13 16:16 ` Erik Iverson
2010-12-13 16:50 ` Tyler Smith
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