Factors

Question 1

Factors

Answer 1

• Variables in R which take on a limited number of different values = known as “categorical” variables.
• Enter into statistical models differently than numerical variaables.

Question 2

How Factors are stored in R

Answer 2

• Stored as a vector of integer values with corresponding set of character values = the character values are displayed.
• An efficient way to store character values.

Question 3

factor()

Answer 3

• Function that creates factors.
• Automatically designates variables as factors during import.
• Numeric + character variables can be converted into factors.
• Factor’s levels will always be displayed as character values.

Question 4

stringsAsFactors =

Answer 4

• An option whose default is set equal to TRUE.

- Turns all the variables imported into factors unless we set = FALSE.

Question 5

knitr

Answer 5

• Package in R which has the function kable which makes seeing factors easier.

Question 6

kable(argument)

Answer 6

• Function in knitr that will display a table where we can see factors above the top rows.

Question 7

as.numeric(object)

Answer 7

• Function that converts the entries of an object into numeric.
• We can use this to convert a factor to numeric.

Question 8

median (argument1,argument2)

Answer 8

• A function that gives the median of some object (such as the column of a data frame).
• The second option can be used to remove NA’s, such as na.rm = TRUE.