R Programming Questions and Answers – Vectorized Operations – 1

This set of R Programming Language Multiple Choice Questions & Answers (MCQs) focuses on “Vectorized Operations – 1”.

1. Which of the following is example of vectorized operation as far as subtraction is concerned?

> x <- 1:4
> y <- 6:9

a) x+y
b) x-y
c) x/y
d) x–y
View Answer

2. Point out the wrong statement?
a) Very less operations in R are vectorized
b) Vectorization allows you to write code that is efficient, concise, and easier to read than in non-vectorized languages
c) vectorized means that operations occur in parallel in certain R objects
d) Matrix operations are also vectorized
View Answer

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

> x <- 1:4
> y <- 6:9
> z <- x + y
> z

a) 7 9 11 13
b) 7 9 11 13 14
c) 9 7 11 13
d) NULL
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4. What will be the output of the following R code?

> x <- 1:4
> x > 2

a) 1 2 3 4
b) FALSE FALSE TRUE TRUE
c) 1 2 3 4 5
d) 5 4 3 1 2 1
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5. Point out the wrong statement?
a) Dates are represented by the Date class
b) Times are represented by the POSIXct or the POSIXlt class
c) Dates are represented by the DateTime class
d) Times can be coerced from a character string
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6. What will be the output of the following R code?

> x <- 1:4
> y <- 6:9
> x/y

a) 0.1666667 0.2857143 0.4444444
b) 0.1666667 0.2857143 0.3750000 0.4444444
c) 0.2857143 0.3750000 0.4444444
d) Error
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7. What will be the output of the following R code?

> x <- matrix(1:4, 2, 2)
> y <- matrix(rep(10, 4), 2, 2)
> x * y

a)

[,1] [,2]
[1,] 10 30
[2,] 20 40

b)

[,1] [,2]
[1,] 10 30
[2,] 30 40

c)

[,1] [,2]
[1,] 20 30
[2,] 20 40

d) Error
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8. Which of the following code represents internal representation of a Date object?
a) class(as.Date(“1970-01-02”))
b) unclass(as.Date(“1970-01-02”))
c) unclassint(as.Date(“1970-01-02”))
d) classint(as.Date(“1970-02-02”))
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9. What will be the output of the following R code?

> x <- as.Date("1970-01-01")
> x

a) “1970-01-01”
b) “1970-01-02”
c) “1970-02-01”
d) “1970-02-02”
View Answer

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

> x <- Sys.time()
> class(x)

a) “POSIXct” “POSIXt”
b) “POSIXXt” “POSIXt”
c) “POSIXct” “POSIct”
d) “POSIXt” “POSIXt”
View Answer

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