R Language MCQs 2

1. If I have two vectors x <- c(1,3, 5) and y <- c(3, 2, 10), what is produced by the expression rbind(x, y)?

A vector of length 2

A 2 by 3 matrix

A vector of length 3

A 2 by 2 matrix

2. If I execute the expression x <- 4 in R language, what is the class of the object “x” as determined by the “class()” function?

Numeric

Complex

Real

Integer

3. _________ is function in R to get number of observation in a data frame

nrow( )

ncol( )

nobs( )

n( )

4. Suppose I have a vector x <- 1:4 and y <- 2:3. What is produced by the expression x + y?

An integer vector with the values 3, 5, 5, 7.

A numeric vector with the values 3, 5, 3, 4.

An error.

A numeric vector with the values 1, 2, 5, 7.

5. In R language the following are all atomic data types EXCEPT

Character

Logical

Data frame

Integer

6. What function is used to test the missing observation in data frame

na( )

NA.miss( )

missing( )

is.na( )

7. The definition of free software consists of four freedoms (freedoms 0 through 3). Which of the following is NOT one of the freedoms that are part of the definition?

The freedom to sell the software for any price.

The freedom to run the program, for any purpose.

The freedom to improve the program, and release your improvements to the public, so that the whole community benefits.

The freedom to study how the program works, and adapt it to your needs.

8. A key property of vectors in R language is that

A vector cannot have attributes like dimensions

Elements of a vector all must be of the same class

Elements of a vector can be of different classes

Elements of a vector can only be a character or numeric

9. Suppose I have a list defined as x <- list(2, “a”, “b”, TRUE). What does x[[2]] give me?

A character vector with the elements “a” and “b”.

A list containing a character vector with the elements “a” and “b”.

A character vector of length 1.

A list containing the number 2 and the letter “a”.

10. What is the class of the object defined by the expression x <- c(4, “a”, TRUE)?

Character

Integer

Logical

Numeric

11. Suppose I have a vector x <- c(3, 5, 1, 10, 12, 6) and I want to set all elements of this vector that are less than 6 to be equal to zero. What R code achieves this?

x[x == 6]

x[x == 0]

x[x

12. The R language is a dialect of which of the following programming languages?

Lisp

Matlab and Mathematica

SAS

R Frequently Asked Questions

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