tryCatch - R Programming

tryCatch lets a script choose a fallback when an expression warns or errors.

Program

Play the script to see invalid text trigger the warning handler and become a fallback value.

try_catch.R

value <- "12x"
number <- tryCatch(as.numeric(value), warning = function(w) NA)
status <- ifelse(is.na(number), "bad", "ok")
cat(status, "\n", sep = "")

tryCatch `tryCatch` handles warnings or errors from an expression.

as.numeric `as.numeric(value)` warns when text is not a clean number.

fallback The warning handler returns `NA`, then the script labels the row `bad`.