Title here
Summary here
Errors in R Programming Language
In R, error handling is typically done through the use of conditions and tryCatch blocks. While R doesn’t have a built-in error type like some other languages, we can create custom error objects and use them in a similar way.
library(stringr)
# Function that may produce an error
f <- function(arg) {
if (arg == 42) {
# In R, we use stop() to signal errors
stop("can't work with 42")
}
# Return a list to mimic multiple return values
list(result = arg + 3, error = NULL)
}
# Custom error objects
ErrOutOfTea <- simpleError("no more tea available")
ErrPower <- simpleError("can't boil water")
# Function that uses custom errors
makeTea <- function(arg) {
if (arg == 2) {
return(ErrOutOfTea)
} else if (arg == 4) {
# To wrap errors in R, we can create a new error with the original as the cause
return(simpleError(str_c("making tea: ", ErrPower$message), call = NULL))
}
NULL
}
# Main execution
main <- function() {
for (i in c(7, 42)) {
# In R, we use tryCatch for error handling
result <- tryCatch({
f(i)
}, error = function(e) {
cat("f failed:", conditionMessage(e), "\n")
return(NULL)
})
if (!is.null(result)) {
cat("f worked:", result$result, "\n")
}
}
for (i in 0:4) {
err <- makeTea(i)
if (!is.null(err)) {
# In R, we can check the class of the error or its message
if (identical(err, ErrOutOfTea)) {
cat("We should buy new tea!\n")
} else if (str_detect(err$message, ErrPower$message)) {
cat("Now it is dark.\n")
} else {
cat("unknown error:", conditionMessage(err), "\n")
}
next
}
cat("Tea is ready!\n")
}
}
main()In this R translation:
We use
stop()to signal errors, which is similar to returning an error in other languages.Custom errors are created using
simpleError().To mimic multiple return values, we return a list with
resultanderrorfields.Error handling is done using
tryCatch()blocks, which is similar to try-catch in other languages.We use
identical()to check for specific errors, andstr_detect()to check for wrapped errors.The
cat()function is used for console output, similar tofmt.Println()in the original code.
When you run this script, you should see output similar to:
f worked: 10
f failed: can't work with 42
Tea is ready!
Tea is ready!
We should buy new tea!
Tea is ready!
Now it is dark.This R code demonstrates error handling, custom errors, and error checking, adapting the concepts from the original code to R’s idioms and conventions.