# 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 into a new factor.

Let’s get started right away!

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## Example: How to add 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

[1] 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.

Consider the following R code:

fac_NA <- addNA(my_fac) fac_NA

[1] a b <NA> a c <NA> # Levels: a b c <NA>

Examine the preceding output: It displays NA as the additional factor level.