Factor Variables

Tip: Always check your answers by typing the commands in R before submission.

Suppose I type the following R commands:

x1 <- rep(c("red","green","blue"),3)

x2 <- rep(c("red","green","blue"),each=3)

a. What is stored in x1?
A character vector containing '"red" "green" "blue" "blue" "green" "red" "red" "green" "blue"' and in that order
A character vector containing '"red" "red" "red" "green" "green" "green" "blue" "blue" "blue"' and in that order
A character vector containing '"red" "green" "blue" "red" "green" "blue" "red" "green" "blue"' and in that order
none of the above

b. What is stored in x2?
A character vector containing '"red" "green" "blue" "red" "green" "blue" "red" "green" "blue"' and in that order
A character vector containing '"red" "green" "blue" "blue" "green" "red" "red" "green" "blue"' and in that order
A character vector containing '"red" "red" "red" "green" "green" "green" "blue" "blue" "blue"' and in that order
none of the above

c. In the expression y1 <- as.factor(x1). What is stored in y1?
A character vector containing '"red" "green" "blue" "red" "green" "blue" "red" "green" "blue"'
A factor vector containing '"red" "red" "red" "green" "green" "green" "blue" "blue" "blue"' with 3 levels: red, green and blue
A factor vector containing 'red green blue red green blue red green blue' with 3 levels: blue, green and red
none of the above

d. In the expression y2 <- factor(x1,levels=c("red","green","blue")), what is stored in y2?
A factor vector containing 'red green blue red green blue red green blue' with 3 levels: red, green and blue
A character vector containing '"red" "green" "blue" "red" "green" "blue" "red" "green" "blue"'
A factor vector containing '"red" "red" "red" "green" "green" "green" "blue" "blue" "blue"' with 3 levels: red, green and blue
none of the above

e. In the expression y3 <- factor(x1,levels=c("black","red","green","blue")), what is stored in y3?
A factor vector containing 'red green blue red green blue red green blue' with 3 levels: red, green and blue
A character vector containing '"red" "green" "blue" "red" "green" "blue" "red" "green" "blue"'
A factor vector containing 'red green blue red green blue red green blue' with 4 levels: black, red, green and blue
none of the above

f. The function as.integer() is applied to the variables x1, y1, y2 and y3. Match the following outputs to the commands.

3 2 1 3 2 1 3 2 1

NA NA NA NA NA NA NA NA NA

2 3 4 2 3 4 2 3 4

1 2 3 1 2 3 1 2 3