R Programming Practice Test 7

1. What will be the output of the following R code?

> f <- function(elt) {
+ elt[, 1]
+ }
> lapply(x, f)

Error

$a
[1] 1 2 3
$b
[1] 1 2

$a
[1] 1 2 3
$b
[1] 1 2 3

$a
[1] 1 2
$b
[1] 1 2 3

2. Which of the following creates a new ggplot plot from a data frame?

ggmissplot

ggplot.data.frame

ggfluctuation

qplot_ggplot

3. Parallel processing is done via __________ package can make the elapsed time smaller than the user time.

parallel

symmetry

statistics

distributed

4. Which of the following is primary tool for debugging?

browser()

debug()

trace()

traceback()

5. The _____ function takes a vector or other objects and splits it into groups determined by a factor or list of factors.

apply()

lsplit()

split()

mapply()

6. Which of the following is valid body of split function?

function (x, f)

function (x, f, drop = FALSE, ...)

function (drop = FALSE, ...)

function (x, drop = FALSE, ...)

7. Point out the correct statement?

Rprof() is used to turn off the profiler

The summaryprof() function tabulates the R profiler output

The Rprofiler() function starts the profiler in R

At each line of the output, the profiler writes out the function call stack

8. What will be the output of the following R code?

 > rpois(10, 1)

 [1] 0 8 1 1 2 1 1 4 1 2

 [1] 7 0 1 1 2 1 1 4 1 2

 [1] 0 0 1 1 2 1 1 4 1 2

 [1] 0 0 0 0 0 0 0 1 4 1 2

9. ______ evaluate the cumulative distribution function for a Normal distribution.

rnorm

rpois

dnorm

pnorm

10. The recover() function will first print out the function call stack when an _______ occurs.

Messages

Error

Warning

delete