R: How to tell lapply to ignore an error and process the next thing in the list?
- by John
I have an example function below that reads in a date as a string and returns it as a date object. If it reads a string that it cannot convert to a date, it returns an error.
testFunction <- function (date_in) {
return(as.Date(date_in))
}
testFunction("2010-04-06") # this works fine
testFunction("foo") # this returns an error
Now, I want to use lapply and apply this function over a list of dates:
dates1 = c("2010-04-06", "2010-04-07", "2010-04-08")
lapply(dates1, testFunction) # this works fine
But if I want to apply the function over a list when one string in the middle of two good dates returns an error, what is the best way to deal with this?
dates2 = c("2010-04-06", "foo", "2010-04-08")
lapply(dates2, testFunction)
I presume that I want a try catch in there, but is there a way to catch the error for the "foo" string whilst asking lapply to continue and read the third date?
