Re: dividing lists...tokenize

Geoffrey King <lordergeoffrey@xxxxxxxxxxxxxxxx> wrote:
+---------------
| My (newbie) go at this is:
| (defun tokenize (token seq &optional result) ...)
| ...
| (tokenize 'A '(1 2 3 A 5 6 A 8 A 10 11))
| ((1 2 3) (5 6) (8) (10 11))
|
| (tokenize 'A '(1 A))
| ((1))
|
| (tokenize 'A '(A 1))
| ((1))
|
| (tokenize 'A '(1 2 3))
| ((1 2 3))
+---------------

Also see <http://www.cliki.net/SPLIT-SEQUENCE>, which can be used
in similar ways, though by default it indicates the results slightly
differently [including a second return value for the index where
processing stopped]:

> (require :split-sequence)

; Loading #p"/u/lisp/contrib/cclan/split-sequence/split-sequence.x86f".
T
> (use-package :split-sequence)

T
> (split-sequence 'A '(1 2 3 A 5 6 A 8 A 10 11))

((1 2 3) (5 6) (8) (10 11))
11
> (split-sequence 'A '(1 A))

((1) NIL)
2
> (split-sequence 'A '(A 1))

(NIL (1))
2
> (split-sequence 'A '(1 2 3))

((1 2 3))
3
>

To get the same results as yours in the 2nd & 3rd test case,
one would use the ":REMOVE-EMPTY-SUBSEQS T" option:

> (split-sequence 'A '(1 A) :remove-empty-subseqs t)

((1))
2
> (split-sequence 'A '(A 1) :remove-empty-subseqs t)

((1))
2
>


-Rob

-----
Rob Warnock <rpw3@xxxxxxxx>
627 26th Avenue <URL:http://rpw3.org/>
San Mateo, CA 94403 (650)572-2607

.