How to Use as.factor() Function in R

The as.factor() function in R is used to convert a vector object to a factor.

Syntax

as.factor(input)

Parameters

input: It takes x as a column in an object of class or data frame.

Return value

It returns a “factor object”.

Example 1: Converting numeric vector to factor

mixed_vec <- c(1.1, 11, 2.2, 19)

as.factor(mixed_vec)

Output

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

Example 2: Converting character vector to factor

char_vec <- c("zack", "john", "jian")

as.factor(char_vec)

Output

[1] zack john jian
Levels: cut synder zack

Example 3: Converting data frame column to factor

df <- data.frame(
  name = c("Krunal", "Ankit", "Rushabh"),
  score = c(85, 90, 78),
  subject = c("Math", "Math", "History"),
  grade = c("10th", "11th", "11th")
)

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

print(df$grade) 

Output

[1] 10th 11th 11th
Levels: 10th 11th

Difference between as.factor() and factor()

The main difference between as.factor() and factor() 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:

That’s it.