Re: new strsplit function

[Rik]

On 03/31/2013 05:38 PM, Ben Abbott wrote:
> Rik,
>
> I've pushed a changeset that includes a note in the NEWS file.
>
>       http://hg.savannah.gnu.org/hgweb/octave/rev/1de4ec2a856d
>
> I have not run any benchmarks.  If it is any help, the new version is based 
> on regexp().
Ben,

Unfortunately regexp is slow compared to operations on native char types.

I did a quick benchmark and I do think this is likely to be an issue.  The
strread function is now 30X slower.

Benchmark Code:
cd scripts/string
tic; A = textread ("strtok.m", "%s"); toc

New results:
1.502 +/- .004

Old results:
0.0455 +/- .0006

Slowdown = 1.502 / .0455 = 33

strtok.m is a small file, 7.2KB, so a largish real data file is going to
parse very slowly.

>
> If we are to add another script, perhaps cstrsplit() is a good names (we did 
> that for strcat some time ago).  Where "c" is for (c)onventional.
That would be a good idea.

Also, shouldn't the replacement of existing instances have been

strsplit (str, del, "collapsedelimiters", false)

rather than

strsplit (str, del, false)

???

I don't see that the Matlab function accepts a third argument--only
PROP/VALUE pairs.

Cheers,
Rik