How to Use the as.factor() Function in R

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Diagram of as.factor() Function in R

Process diagram of as.factor() method

The as.factor() function in R is “used to convert a vector object to factor”. It takes a vector as a mandatory argument and returns a factor object.

Syntax

as.factor(input)

Parameters

input: The as.factor() function takes x as a column in an object of class or data frame.

Return value

The as.factor() function returns a “factor object”.

Example 1: Converting numeric vector to factor

data <- c(1.1, 11, 2.2, 19, 21)

as.factor(data)

Output

[1] 1.1 11 2.2 19 21
Levels: 1.1 2.2 11 19 21

Example 2: Converting character vector to factor

data <- c("zack", "synder", "cut")

as.factor(data)

Output

[1] zack synder cut
Levels: cut synder zack

Example 3: Converting data frame column to factor

You can use the as.factor() function to convert a specific data frame column to a factor.

df <- data.frame(Singer = c("MJ", "Justin", "Drake", "Selena", "Rema", "Ed"),
                    Age = c(64, 30, 40, 30, 25, 38))

df$Singer <- as.factor(df$Singer)

print(df$Singer)

Output

[1] MJ Justin Drake Selena Rema Ed
Levels: Drake Ed Justin MJ Rema Selena

Difference between as.factor() and factor() in R

The main difference between as.factor() and factor() in R is that as.factor() is an abbreviated form of factor() that can sometimes run faster. The as.factor() coerces its argument to a factor, while factor() allows for more optional arguments.

Based on my experience, I created a table that summarizes the key differences between the two functions:

Function Description
as.factor() Converts its argument to a factor.
factor() Converts its argument to a factor and allows for more optional arguments, such as levels, ordered, and exclude.

That’s it.

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