How to add NA values into a factor level
How to add NA values into a factor level, This article describes how to use the addNA function in the R programming language to convert NA values into a new factor level.
Let’s get started right away!
Example: Turn NA values into a factor level
The following data will serve as the foundation for this R tutorial.
fac <- factor(c("a", "b", NA, "a", "c", NA)) fac
 a b <NA> a c <NA> Levels: a b c
The structure of our example data is shown in the previous RStudio console output: We made a factor vector out of the three-factor levels a, b, and c.
In addition, our factor contains some NA values (i.e. missing data).
Example: Using the addNA() function, convert NA to Extra Factor Level.
In this example, We’ll show how to use R’s addNA function to convert NA values to a new factor level.
Consider the following R code:
fac_NA <- addNA(my_fac) fac_NA
 a b <NA> a c <NA> # Levels: a b c <NA>
Examine the preceding output: It displays NA as the additional factor level.