Error handling (tryCatch) in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch errors using tryCatch.

R Programming

result <- tryCatch({
  log('a')
}, error = function(e) {
  [1]
})

Drag options to blanks, or click blank then click option'

Awarning('Error caught!')

Blog(1)

Cprint('Error caught!')

Dstop('Error caught!')

Attempts:

3 left

💡 Hint

Common Mistakes

Using stop() inside the error handler will re-throw the error.

Not defining a function for the error argument.

Using warning() instead of print() does not stop the error.

The error argument in tryCatch defines a function to run when an error occurs. Using print('Error caught!') will display the message when the error happens.

2fill in blank

medium

Complete the code to return a default value when an error occurs.

R Programming

safe_log <- function(x) {
  tryCatch(log(x), error = function(e) [1])
}

safe_log('a')

Drag options to blanks, or click blank then click option'

AInf

BNULL

C0

DNA

Attempts:

3 left

💡 Hint

Common Mistakes

Returning NULL can cause issues if the caller expects a numeric value.

Returning 0 or Inf may mislead the user about the result.

Returning NA is a common way to indicate a missing or invalid result when an error occurs.

3fill in blank

hard

Fix the error in the tryCatch usage to properly handle warnings.

R Programming

result <- tryCatch({
  sqrt(-1)
}, warning = function(w) {
  [1]
})

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Aprint('Warning caught!')

Bstop('Warning caught!')

Creturn(NA)

Dmessage('Warning caught!')

Attempts:

3 left

💡 Hint

Common Mistakes

Using stop() inside warning handler re-throws the warning as an error.

Using message() may not be visible depending on console settings.

The warning handler function should print a message or handle the warning gracefully. Using print('Warning caught!') shows the warning was caught.

4fill in blank

hard

Fill both blanks to catch errors and return a message.

R Programming

result <- tryCatch({
  log('a')
}, error = function(e) {
  [1]
}, finally = {
  [2]
})

Drag options to blanks, or click blank then click option'

Areturn('Error handled')

Bprint('Cleaning up')

Cstop('Error handled')

Dmessage('Cleaning up')

Attempts:

3 left

💡 Hint

Common Mistakes

Using stop() in error handler re-throws the error.

Using message() in finally may not always show output.

The error handler returns a message string. The finally block runs cleanup code, here printing a message.

5fill in blank

hard

Fill all three blanks to catch errors, warnings, and run final code.

R Programming

result <- tryCatch({
  log(-10)
}, error = function(e) {
  [1]
}, warning = function(w) {
  [2]
}, finally = {
  [3]
})

Drag options to blanks, or click blank then click option'

Areturn(NA)

Bprint('Warning caught')

Cprint('Cleaning up')

Dstop('Error caught')

Attempts:

3 left

💡 Hint

Common Mistakes

Using stop() in error handler causes the program to stop.

Not printing messages in warning or finally blocks hides useful info.

The error handler returns NA to handle errors gracefully. The warning handler prints a message. The finally block prints a cleanup message.