Don't bother putting the 'zest[i]<-' into the error handler: the
retun value of the handler will be the return value of tryCatch:
E.g.,
> tryCatch(stop("Oops"), error=function(cond)NA,
warning=function(cond)-1)
[1] NA
> tryCatch(warning("Hmm"), error=function(cond)NA,
warning=function(cond)-1)
[1] -1
> tryCatch(log(10), error=function(cond)NA, warning=function(cond)-1)
[1] 2.302585
Usually people put the call to tryCatch inside the call to sapply
so you can recover from errors in any iteration of the loop in
sapply.
> sapply(1:5,
FUN=function(i) {
tryCatch(
if(i%%2==0) {
stop("i is even")
} else {
(i-1)/2
},
error=function(cond)NA)
})
[1] 0 NA 1 NA 2
but you may have good reason to want to return a single NA if any
iteration of sapply causes an error.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of eric
> Sent: Sunday, July 10, 2011 9:25 AM
> To: r-help@r-project.org
> Subject: [R] Help with tryCatch
>
> Having a hard time understanding the help files for tryCatch.
> Looking for a
> little help with the following statement which sits inside a for loop
>
> zest[i] <- tryCatch(sapply(getNodeSet(zdoc, "//zestimate/amount"),
> xmlValue), error=function() zest[i] <-"NA")
>
> zest is a numeric vector
>
> If the sapply statement evaluates to an error, I'd like to
> set the value of
> zest[i] to NA and continue with the loop.
>
> Suggestions ?
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/Help-with-tryCatch-tp3657859p365
7859.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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