R help - Oct 2008 - ignore error in for-loop

Hi all,

Can anybody tell me what to do in case an error occurs inside a 
for-loop and I don't want the program to exit the loop? Rather 
instead I would like it to just go to the next number in the loop and 
try again with the new number. Is there any function like "on error 
go back to" or "skip error" ... ?

Thanks in advance,
Erich



Erich STRIESSNIG
IIASA
International Institute for Applied Systems Analysis
A-2361 Laxenburg, Austria
E-Mail: striess at iiasa.ac.at
Phone : +43 2236 807-0
Fax   : +43 2236 71313

Dear Erich,

Have a look at the try()-function.

HTH,

Thierry 


------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
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tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be 
www.inbo.be 

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than asking him to perform a post-mortem examination: he may be able to
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-----Oorspronkelijk bericht-----
Van: r-help-bounces op r-project.org [mailto:r-help-bounces op r-project.org]
Namens Erich STRIESSNIG
Verzonden: maandag 6 oktober 2008 15:04
Aan: r-help op r-project.org
Onderwerp: [R] ignore error in for-loop

Hi all,

Can anybody tell me what to do in case an error occurs inside a 
for-loop and I don't want the program to exit the loop? Rather 
instead I would like it to just go to the next number in the loop and 
try again with the new number. Is there any function like "on error 
go back to" or "skip error" ... ?

Thanks in advance,
Erich



Erich STRIESSNIG
IIASA
International Institute for Applied Systems Analysis
A-2361 Laxenburg, Austria
E-Mail: striess op iiasa.ac.at
Phone : +43 2236 807-0
Fax   : +43 2236 71313

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Erich STRIESSNIG wrote:
> Hi all,
>
> Can anybody tell me what to do in case an error occurs inside a
> for-loop and I don't want the program to exit the loop? Rather instead
> I would like it to just go to the next number in the loop and try
> again with the new number. Is there any function like "on error go
> back to" or "skip error" ... ?
there's the keyword 'next' in r which you could use to proceed to
the
next value in a for loop.
you can also use try({...}) within the loop, e.g.:

for (i in 0:3)
   try({if (i==2) stop(i); print(i)}, silent=TRUE)

[1] 0
[1] 1
[1] 3

vQ