R help - Jul 2009 - I might be dumb : a simple question about "foreach"

Hi list,
My attention was drawn to the foreach package by recent posts...I 
decided to have a look...
I'm using R.2.9.1 on Windows, I have downloaded the foreach package 
today (v 1.2.1), together with iterators (v. 1.0.1) and codetools (v.0.2-2).
Full of hope I try the most simple thing of all out of the package 
vignette :
>  x <- foreach(i = 1:3) %do% sqrt(i)
and get :
> Erreur dans sqrt(i) : indice hors limites ( i.e. "error in sqrt(i) : 
> index out of bounds")
but when trying :
> x<-foreach(i = 1:3) %do% print(sqrt(i))
I get :
> [1] 1
> [1] 1.414214
> [1] 1.732051
> Erreur dans print(sqrt(i)) : indice hors limites
Probably I didn't drink enough coffee this morning and I'm still asleep 
: it is obvious that  I miss a point... but I am unable to see which one.
Any help appreciated ! Many thanks, and very best regards Olivier

-- 
Olivier ETERRADOSSI
Ma?tre-Assistant
CMGD / Equipe "Propri?t?s Psycho-Sensorielles des Mat?riaux"
Ecole des Mines d'Al?s
H?lioparc, 2 av. P. Angot, F-64053 PAU CEDEX 9
tel std: +33 (0)5.59.30.54.25
tel direct: +33 (0)5.59.30.90.35 
fax: +33 (0)5.59.30.63.68
http://www.ema.fr

On Mon, Jul 20, 2009 at 2:48 PM, Olivier
ETERRADOSSI<Olivier.Eterradossi at ema.fr> wrote:
>> ?x <- foreach(i = 1:3) %do% sqrt(i)
>
> and get :
>>
>> Erreur dans sqrt(i) : indice hors limites ( i.e. "error in sqrt(i)
: index
>> out of bounds")
I once got similar errors because I didn't encapsulate the part af
%do% or %dopar% in curly brackets. Try

x <- foreach(i = 1:3) %do% { sqrt(i) }

I should say, however, that in this particular case, your original
code evaluates without errors on my computer (Mac OSX 10.5.7 with R
2.9.1).

By the way, remember to use %dopar% instead of %do%, if you want to
take advantage of multiple cores. While being totally ecstatic after
discovering foreach, I wrote the following (very simple) guide:

http://lifeofknudsen.blogspot.com/2009/07/most-of-work-i-do-in-r-has-to-do-with.html

Maybe you'll find it useful, maybe not.

-- 
Michael Knudsen
micknudsen at gmail.com
http://lifeofknudsen.blogspot.com/

A user in Japan reported a similar problem on the Revolutions blog (
http://bit.ly/FKP2I ), and my best guess is that it's an (unintended!)
effect of using locales. The developers in New Haven are looking at it, and
I expect they'll be able to post an update to CRAN soon.
# David Smith

On Mon, Jul 20, 2009 at 5:48 AM, Olivier ETERRADOSSI <
Olivier.Eterradossi@ema.fr> wrote:
> Hi list,
> My attention was drawn to the foreach package by recent posts...I decided
> to have a look...
> I'm using R.2.9.1 on Windows, I have downloaded the foreach package
today
> (v 1.2.1), together with iterators (v. 1.0.1) and codetools (v.0.2-2).
> Full of hope I try the most simple thing of all out of the package vignette
> :
>
>>  x <- foreach(i = 1:3) %do% sqrt(i)
>>
> and get :
>
>> Erreur dans sqrt(i) : indice hors limites ( i.e. "error in sqrt(i)
: index
>> out of bounds")
>>
> but when trying :
>
>  x<-foreach(i = 1:3) %do% print(sqrt(i))
>>
> I get :
>
>  [1] 1
>> [1] 1.414214
>> [1] 1.732051
>> Erreur dans print(sqrt(i)) : indice hors limites
>>
> Probably I didn't drink enough coffee this morning and I'm still
asleep :
> it is obvious that  I miss a point... but I am unable to see which one.
> Any help appreciated ! Many thanks, and very best regards Olivier
>
> --
> Olivier ETERRADOSSI
> Maître-Assistant
> CMGD / Equipe "Propriétés Psycho-Sensorielles des Matériaux"
> Ecole des Mines d'Alès
> Hélioparc, 2 av. P. Angot, F-64053 PAU CEDEX 9
> tel std: +33 (0)5.59.30.54.25
> tel direct: +33 (0)5.59.30.90.35 fax: +33 (0)5.59.30.63.68
> http://www.ema.fr
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
David M Smith <david@revolution-computing.com>
Director of Community, REvolution Computing www.revolution-computing.com
Tel: +1 (206) 577-4778 x3203 (San Francisco, USA)

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