MCQs R Debugging 6 - R Frequently Asked Questions

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

browser( )

try( )

stop( )

tryCatch( )

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

browser( )

trace( )

debug( )

recover( )

3. Debugging is the process of

Writing code that is as fast as possible

Writing code that uses memory efficiently

Handling errors in a nonstandard manner

Getting your expectations about code behavior to converge with reality

4. What is the microbenchmark package useful for?

Interactively debugging functions

Comparing the speed of several functions that do the same thing

Modifying code in other developers’ packages

Handling warnings and errors in non-standard ways

5. What does the traceback( ) function do?

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

Pauses execution of a function

Sets the debugging flag for a function

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

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

profvis( )

Both profvis( ) and microbenchmark( )

microbenchmark( )

None of profvis( ) and microbenchmark( )

7. What does the profvis( ) function do?

Prints debugging information to the console

Displays profiling information in an interactive visualization in RStudio

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

Writes a log file of the function call stack

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

Immediately after an error occurs

Only while debugging inside a function

Any time after an error occurs

Immediately after a warning occurs

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

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

It generates a log file containing debugging information.

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

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

10. What does the Rprof( ) function do?

Analyzes your code for potential bugs

Visualizes the time behavior of R code

Re-formats your code to adhere to standards

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

R Frequently Asked Questions

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