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How do I stop/end/halt a script in R?

I wrote a script that should stop execution if the supplied data is incorrect. However, although stop produces an error message, the script just continues. A minimal example:

if (TRUE) {stop("End of script?")} #It should stop here
print("Script did NOT end!") # but it doesn't, because this line is printed!

Console output:

> if (TRUE) {stop("End of script?")}
Error: End of script?
> print("Script did NOT end!")
[1] "Script did NOT end!"
>

This is actually not surprising, because from ?stop:

stops execution of the current expression and executes an error action.

So it only ends the current expression, not the script. I have found here that you can wrap {} around the total script (or put it in a function), but that seems rather a workaround than a solution. Off course, it is good programming practice to catch error and handle them off yourself (see for example the link in comment from mra68), but I would still like to know if I can stop a script in R.

I have also tried return and break, but this only works in a function or loop. I searched for other possible keywords like "halt" and "end", but no luck. I am feeling a bit stupid, because it seems a very basic question.

So, is there a command that can make my script halt/stop/end with a fatal error ?

I am running R 3.2.3 on Windows 8, but had the same problem with R 3.0.1 at MAC-OSX.

> sessionInfo()
R version 3.2.3 (2015-12-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)

locale:
[1] LC_COLLATE=Dutch_Netherlands.1252  LC_CTYPE=Dutch_Netherlands.1252    LC_MONETARY=Dutch_Netherlands.1252
[4] LC_NUMERIC=C                       LC_TIME=Dutch_Netherlands.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
[1] tools_3.2.3

TEST ON MAC-OS, sessionInfo()

R version 3.0.1 (2013-05-16)
Platform: x86_64-apple-darwin10.8.0 (64-bit)

locale:
[1] nl_NL.UTF-8/nl_NL.UTF-8/nl_NL.UTF-8/C/nl_NL.UTF-8/nl_NL.UTF-8
Solution

  • As far as I could find, there is no single command that really stops a script on every platform/version. There are several ways to handle this:

    Put it in a function or curly brackets:

    {
if (TRUE) {stop("The value is TRUE, so the script must end here")}

print("Script did NOT end!")
}

    OR evaluate the error and handle it like in an if else construction:

    if (TRUE) {stop("The value is TRUE, so the script must end here")    
  } else { #continue the script
print("Script did NOT end!")   
  }

    OR (EDIT): Another possibility is to call the script from a seperate 'main' R-scipt, with source("MyScript.R"). Then the script terminates. This however, suppresses all output other then errors to the console.

    OR for more complex operations, use tryCatch() as shown here