What is an R Factor?

A factor in R is a data structure used for handling categorical data, which is data that can take on a limited, fixed number of possible values. Factors are often used to represent categories such as “Male” and “Female,” “Yes” and “No,” or other groups where the number of levels is predefined.

# Creating a factor in R
gender <- factor(c("Male", "Female", "Female", "Male"))

# Printing the factor
print(gender)

# Output:
# [1] Male   Female Female Male
# Levels: Female Male

In this example, a factor named gender is created with two levels: “Female” and “Male.” The factor stores the categorical data as integers under the hood, while maintaining a mapping to the original character strings.

Factors are important in statistical modeling and data analysis in R because they allow you to categorize data effectively and perform operations that take these categories into account.