MCQs R Debugging 6 - R Frequently Asked Questions

1. Which of the following functions allows you to temporarily insert pieces of code into other functions to modify their behavior?

browser( )

recover( )

debug( )

trace( )

2. When should the traceback( ) function be called?

Any time after an error occurs

Immediately after a warning occurs

Immediately after an error occurs

Only while debugging inside a function

3. Debugging is the process of

Getting your expectations about code behavior to converge with reality

Writing code that uses memory efficiently

Writing code that is as fast as possible

Handling errors in a nonstandard manner

4. What does the Rprof( ) function do?

Visualizes the time behavior of R code

Re-formats your code to adhere to standards

Analyzes your code for potential bugs

Writes out the function call stack at user-specified intervals of time

5. What does calling trace(“f”) for function “f( )” do

Whenever f( ) is called, a message is printed to the console indicating that the function was called.

It generates a log file containing debugging information.

Whenever f( ) is called, it will enter the interactive debugger.

Whenever f( ) is called, the function call stack is written to a file.

6. What is the microbenchmark package useful for?

Interactively debugging functions

Handling warnings and errors in non-standard ways

Comparing the speed of several functions that do the same thing

Modifying code in other developers’ packages

7. Which of the following functions initiates an interactive debugging environment that allows you to step through code one expression at a time?

tryCatch( )

try( )

stop( )

browser( )

8. Which function is better for analyzing fast-running functions: profvis( ) or microbenchmark( )?

profvis( )

Both profvis( ) and microbenchmark( )

None of profvis( ) and microbenchmark( )

microbenchmark( )

9. What does the traceback( ) function do?

Returns the state of the function call stack just before an occurred

Sets the debugging flag for a function

Evaluates an expression and returns on the object of “try-error” if an error occurs

Pauses execution of a function

10. What does the profvis( ) function do?

Visualizes code that runs quickly (in less than 10 milliseconds)

Displays profiling information in an interactive visualization in RStudio

Prints debugging information to the console

Writes a log file of the function call stack

R Frequently Asked Questions

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