R Language MCQs 2 - R Frequently Asked Questions

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

Lisp

Matlab and Mathematica

SAS

2. 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 only be a character or numeric

Elements of a vector can be of different classes

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

An error.

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

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

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

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

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

A character vector of length 1.

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

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

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

na( )

NA.miss( )

is.na( )

missing( )

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

Numeric

Character

Logical

Integer

7. 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 2 by 2 matrix

A 2 by 3 matrix

A vector of length 2

A vector of length 3

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

Real

Numeric

Integer

Complex

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

The freedom to sell the software for any price.

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

The freedom to run the program, for any purpose.

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

Character

Data frame

Logical

Integer

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

x[x == 6]

x[x == 0]

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

n( )

nobs( )

nrow( )

ncol( )

R Frequently Asked Questions

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