Reorder Levels of Factor without Changing Order of Values in R (Example)

In this article you’ll learn how to reorder factor levels in the R programming language.

The tutorial looks as follows:

• Introduction of Example Data
• Example: Reorder Factor Levels without Losing the Order of Values
• Video & Further Resources

If you want to learn more about these topics, keep reading:

Introduction of Example Data

As a first step, we need to create a factor vector in R as basement for the following example:

x <- factor(c("a", "BBB", "A", "CC"))           # Create example factor
x                                               # Print factor values and levels
# [1] a   BBB A   CC 
# Levels: a A BBB CC

Our example factor consists of four values and four factor levels. The factor levels are sorted alphabetically, i.e. a A BBB CC.

Now, let’s change the order of these factor levels…

Example: Reorder Factor Levels without Losing the Order of Values

If we want to modify the ordering of the factor levels of our example vector, then we can use the following R syntax:

x_mod <- factor(x, c("BBB", "CC", "a", "A"))    # Modify factor levels
x_mod                                           # Print modified values and levels
# [1] a   BBB A   CC 
# Levels: BBB CC a A

As you can see, we specified the order of the levels manually within the factor function. The factor levels of the updated factor vector are BBB CC a A. However, the order of the values of our vector were preserved.

Video & Further Resources

Would you like to learn more about factor vectors in R? Then you may watch the following video instruction of my YouTube channel. I show the R codes of this tutorial in the video:

In addition, you may read some of the other articles on this website. You can find some interesting posts here:

• Drop Factor Levels of Vector & Data Frame
• Warning: invalid factor level, NA generated
• recode & recode_factor R Functions of dplyr Package
• The R Programming Language

Summary: This article illustrated how to reorder factor levels, but preserve the order of values in R programming. Don’t hesitate to let me know in the comments section, in case you have further questions.