[R] Help with tryCatch with a for loop

[William Dunlap]

If your loop is of the form

for(i in 1:n) {
   doSomethingSafe()
   x <- doSomethingThatFailsSometimes()
   doSomethingWithX(x) # cannot do this if previous line fails
   doSomethingElseSafe()
}

and you want it to somehow recover when
doSomethingThatFailsSometimes() throws an error,
then change it to use try() with

for(i in 1:n) {
   doSomethingSafe()
   tmp <- try({
      x <- doSomethingThatFailsSometimes()
      doSomethingWithX(x)
   })
   if (inherits(try, "try-error")) {
      recoverFromFailure()
   }
   doSomethingElseSafe()
}

or to use tryCatch() with

for(i in 1:n) {
   doSomethingSafe()
   tryCatch({
      x <- doSomethingThatFailsSometimes()
      doSomethingWithX(x)
   }, error = function(e) {
      message("Had a problem at iteration ", i, ": ", conditionMessage(e))
      recoverFromFailure()
   })
   doSomethingElseSafe()
}
   

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Spencer S
> Sent: Wednesday, November 09, 2011 2:57 PM
> To: r-help at r-project.org
> Subject: Re: [R] Help with tryCatch with a for loop
> 
> My apologies for not including some test data.
> Attached is a sample dataset that fails with the first stateroute and works
> with the second.
> 
> http://r.789695.n4.nabble.com/file/n4021696/testdata.csv testdata.csv
> 
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/Help-with-tryCatch-with-a-for-loop-
> tp4020475p4021696.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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