The quick and dirty way to do so is to use: stopifnot() in conjunction (if necessary with all() and any()). You can replace that first condition with a simple is.numeric() as well. A more helpful way (if this is production code) is to use if statement with the stop() function directly which lets you provide specific error messages.
Michael On Tue, Dec 6, 2011 at 6:41 AM, Johannes Radinger <jradin...@gmx.at> wrote: > Hi, > > I just started with writing functions in R and so some questions popped up. > I provide some values as argument to my function such as: > > function(a,b,c){} > > Now i want that the function first checks if the arguments are valid for the > function. E.g argument "a" has to be a number in the range 0-1. How can that > easily done? > > So far I have: > > a <- as.numeric(a) > if(0 <= a && a <= 1) > > to first check if a is a number...if not the function stops and gives an > error message. If it is a number it just continues... > > But how to check the range? > Above there is the if-approach but then the rest of the function is exectued > as part of if (or else). Is there a simpler way without having the > if-brackets around the remaining code? > Just a check if the value is between 0 and 1 and if yes continue with the > next line if no abort the function with a error message? How can such an > error message be created? > > thank you and best regards, > > /Johannes > -- > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.