R Programming MCQ: R Programming Multiple Choice Questions

R Programming MCQ with answers and explanations for placement tests and job interviews. These solved R Programming MCQ questions are useful for the campus placement for all freshers including Engineering Students, MCA students, Computer and IT Engineers, etc.

Our R Programming MCQ ( R Programming Multiple Choice Questions and Answer ) focuses on all areas of R Language Programming. We will also regularly update the R Programming MCQ and most interesting thing is that questions come in a random sequence. So every time you will feel new questions.

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So let’s see our R Programming MCQ (Multiple Choice Questions & Answers on “R Programming”).

R Programming MCQ: R Programming Multiple Choice Questions

1 / 42

Which of the following will start the R program?

> R

$ R

* R

@ R

2 / 42

Review the statements below. Does the use of the dim function change the class of y, and if so what is y's new class?

> y <- 1:9
> dim(y) <- c(3,3)

No, y's new class is "array".

Yes, y's new class is "matrix".

No, y's new class is "vector".

Yes, y's new class is "integer".

3 / 42

What do you use to take an object such as a data frame out of the workspace?

remove()

erase()

detach()

delete()

4 / 42

If the code is stored in the external file, which of the following function is used to call them to a working directory?

exec()

source()

execute()

sourcefile()

5 / 42

Which is not a property of lists and vectors?

type

length

attributes

scalar

6 / 42

Review line 1 below. What does the statement in line 2 return?

1 mylist <- list(1,2,"C",4,5)
2 unlist(mylist)

[1] 1 2 4 5

[1] "1" "2" "C" "4" "5"

[1] 1 2 C 4 5

"C"

7 / 42

ournames is a character vector. What values does the statement below return to Cpeople?

Cpeople <- ournames %in% grep("^C", ournames, value=TRUE)

records where the first character is a C

TRUE or FALSE, depending on whether any character in ournames is C

TRUE or FALSE values, depending on whether the first character in an ournames record is C

any record with a value containing a C

8 / 42

d.pizza is a data frame. It's column named temperature contains only numbers. If u extract temperature using the [] accessors, its class defaults to numeric. How can you access temperature so that it retains the class of data.frame?

> class( d.pizza[ , "temperature" ] )
> "numeric"

class( d.pizza$temperature )

class( d.pizza[ , "temperature", drop=F ] )

class( d.pizza( , "temperature" ) )

class( d.pizza[ , "temperature" ] )

9 / 42

Given DFMerged <- merge(DF1, DF2) and the image below, how manu rows are in DFMerged?

DF1(data frame 1): DF2(data frame 2):
VarA VarB VarA VarD
1 1 2 1 18 21
2 4 5 2 19 22
3 7 8 3 20 23

10 / 42

_____ text editor provides more general support mechanisms via ESS for working interactively with R.

EAC

Emacs

Shell

ECAP

11 / 42

Which choice does R regard as an acceptable name for a variable?

Var_A!

\_VarA

.2Var_A

Var2_A

12 / 42

What is the output of getOption(“defaultPackages”) in R studio?

Installs a new package

Shows default packages in R

Error

Nothing will print

13 / 42

Point out the wrong statement?

Setting up a workstation to take full advantage of the customizable features of R is a straightforward thing

q() is used to quit the R program

R has an inbuilt help facility similar to the man facility of UNIX

Windows versions of R have other optional help systems also

14 / 42

What statement shows the objects on your workspace?

list.objects()

getws()

ls()

print.objects()

15 / 42

A single element of a character vector is referred as ________

Character string

String

Data strings

Raw data

16 / 42

You accidentally display a large data frame on the R console, losing all the statements you entered during the current session. What is the best way to get the prior 25 statements back?

history(max.show = 25)

console(-25)

history()

console(reverse=TRUE)

17 / 42

What is the function to set row names for a data frame?

row.names()

colnames()

col.names()

column name cannot be set for a data frame

18 / 42

The most convenient way to use R is at a graphics workstation running a ________ system.

windowing

running

interfacing

matrix

19 / 42

What is the value of names(v[4])?

v <- 1:3
names(v) <- c("a", "b", "c")
v[4] <- 4

NULL

20 / 42

Elementary commands in R consist of either _______ or assignments.

utilstats

language

expressions

packages

21 / 42

R files has an extension ______

.RP

22 / 42

How many atomic vector types does R have?

23 / 42

What is the value of y in this code?

x <- NA
y <- x/1

Inf

Null

NaN

24 / 42

How to name rows and columns in DataFrames and Matrices F in R?

data frame: names() and rownames() matrix: colnames() and row.names()

data frame: names() and row.names() matrix: dimnames() (not sure)

data frame: colnames() and row.names() matrix: names() and rownames()

data frame: colnames() and rownames() matrix: names() and row.names()

25 / 42

What is the principal difference between an array and a matrix?

A matrix has two dimensions, while an array can have three or more dimensions.

An array is a subtype of the data frame, while a matrix is a separate type entirely.

A matrix can have columns of different lengths, but an array's columns must all be the same length.

A matrix may contain numeric values only, while an array can mix different types of values.

26 / 42

If a command is not complete at the end of a line, R will give a different prompt, by default it is ____________

27 / 42

What function joins two or more column vectors to form a data frame?

rbind()

cbind()

bind()

coerce()

28 / 42

Advanced programmers can write ______ code to manipulate R objects.

Python

JavaScript

Java

29 / 42

Two variable in the mydata data frame are named Var1 and Var2. How do you tell a bivariate function, such as cor.test, which two variables you want to analyze?

cor.test(Var1 ~ Var2)

cor.test(mydata$(Var1,Var2))

cor.test(mydata$Var1,mydata$Var2)

cor.test(Var1,Var2, mydata)

30 / 42

What does c contain?

a <- c(3,3,6.5,8)
b <- c(7,2,5.5,10)
c <- a < b

[1] NaN

[1] -4

[1] 4 -1 -1 2

[1] TRUE FALSE FALSE TRUE

31 / 42

Which function displays the first five rows of the data frame named pizza?

BOF(pizza, 5)

first(pizza, 5)

top(pizza, 5)

head(pizza, 5)

32 / 42

Functionality of R is divided into a number of __________

Functions

Domains

Packages

Files

33 / 42

How does a matrix differ from a data frame?

A matrix may contain numeric values only.

A matrix must not be singular.

A data frame may contain variables that have different modes.

A data frame may contain variables of different lengths.

34 / 42

Which of the following statements doesn't yield the code output below. Review the following code. What is the result of line 3?

x <- c(1, 2, 3, 4)
Output: [1] 2 3 4

x[c(2, 3, 4)]

x[-1]

x[c(-1, 0, 0, 0)]

x[c(-1, 2, 3, 4)]

35 / 42

Which of the following statement is alternative to _________?

solve

help(solve)

print(solve)

bind(solve)

matrix(solve)

36 / 42

Which of the following is default prompt for UNIX environment?

37 / 42

unclass(as.Date("1971-01-01"))

365

38 / 42

A data frame named d.pizza is part of the DescTools package. A statement is missing from the following R code and an error is therefore likely to occur. Which statement is missing?

library(DescTools)
deliver <- aggregate(count,by=list(area,driver), FUN=mean)
print(deliver)

attach(d.pizza)

summarize(deliver)

mean <- rbind(d.pizza,count)

deliver[!complete.cases(deliver),]

39 / 42

The variable height is a numeric vector in the code below. Which statement returns the value 35?

height(length(height))

height[length(height)]

height[length[height]]

height(5) Q6. In the ima

40 / 42

How does a vector differ from a list?

Vectors and lists are the same thing and can be used interchangeably.

Vectors are used only for numeric data, while list are useful for both numeric and string data.

Vectors are like arrays, while lists are like data frames.

A vector contains items of a single data type, while a list can contain items of different data types.

41 / 42

Review the following code. What is the result of line 3?

xvect<-c(1,2,3)
xvect[2] <- "2"
xvect

[1] 1 2 3

[1] "1" 2 "3"

[1] "1" "2" "3"

[1] 7 9

42 / 42

What is mydf$y in this code?

mydf <- data.frame(x=1:3, y=c("a","b","c"), stringAsFactors=FALSE)

list

string

factor

character vector

Your score is

R Programming MCQ: R Programming Multiple Choice Questions

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