R Programming Practice Test 3

1. What is the simplest way of creating the vector?

C function

Create

Destroy

Invalid

2. Which of the following statement would read file "foo.txt"?

data <- read.table("foo.txt")

data <- data("foo.txt")

read.data <- read.table("foo.txt")

data <- read.data("foo.txt")

3. Which of the following is valid assignment?

 > x <- factor(factor("yes", "no", "no", "yes", "no"))

 > x <- factor(factor("yes", "yes", "no", "yes", "no"))

 > x <- factor(c("yes", "yes", "no", "yes", "no"))

 > x <- fact(c("yes", "yes", "no", "yes", "no"))

4. The ________ stores the nominal values as a vector of integers in the range of 1 to unique values in the nominal variable.

Lists

Functions

Matrix

Factor

5. Point out the wrong statement?

dump is used for for dumping a textual representation of multiple R objects

writeLines is used for for writing character data line-by-line to a file or connection

all of the mentioned

write.table is used for for writing tabular data to text files (i.e. CSV) or connections

6. The _________ function returns a list of densities (y) corresponding to bin values (x).

Spline

Density

Lists

Locator

7. Which function can be used to determine the names assigned to a list?

Names

Nem

Nam

Name

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

> x <- 1:3
> names(x)

NULL

4.5

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

> x <- 1:3
> y <- 10:12
> rbind(x, y)

[,1] [,2] [,3]
x 1 2 3
y 10 11 12

[,1] [,2] [,3]
x 1 2 3
y 10 11

[,4] [,5] [,3]
x 1 3 5
y 4 5 2

[,1] [,2] [,3]
x 1 2 3
y 4 5 6

10. Factors are created using the _______ function.

Lists()

Function()

Array()

C()