[R] catching errors in a loop

[Uwe Ligges]

Anders Bjørgesæter wrote:
> Hello
> 
> I can't figure out how to handle errors in R. I have a loop, e.g.
> 
> for (i in 2:n) {
> .
> fit <- nls(model), start=list…
> if any type of error occur write i to a text file
> .
> }
> 
> I putted “try” around the nls-expression and this let me run through the 
> loop without R stopping (which I want because each loop takes some time so 
> I do not want it to stop), but I also want to capture the variable when an 
> error occur.

Right idea:

   fit <-  try(nls(model, .....))
   if(inherits(fit, "try-error"))
	write(i, file="hello.txt")

Uwe Ligges





> 
> Appreciate any help
> 
> /Anders
> - - - - - - - - - - - - - - - - - - -
> I tried to use:
> **“options(error=write(variable.names(matrix[i]), 
> file="..\\error.txt",append = TRUE))”, hoping this made R write to the text 
> file every time an error occurred (but this made R write all i’s in the 
> loop to the text file).
> **tryCatch(<- nls(model), start=list…), finally =write(…) also writes to a 
> text file but not necessary when there is an error.
> **“if (Parameter>x errorM=9 else errorM =0” works but I want to capture any 
> type of error.
> - - - - - - - - - - - - - - - - -
> 
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