Replace Character Value with NA in R (2 Examples)
In this tutorial, I’ll show how to replace characters in vectors and data frame columns by NA in the R programming language.
Table of contents:
Let’s get started!
Example 1: Replace Specific Character Value with NA in Vector
In Example 1, I’ll illustrate how to set particular characters in a vector to NA (i.e. missing value).
Consider the following example vector in R:
vec <- c("A", "B", "A", "C", "B") # Create example vector vec # Print example vector #  "A" "B" "A" "C" "B"
As you can see based on the previous output of the RStudio console, our example vector contains a sequence of uppercase letters.
Let’s assume that we want to exchange the character letter “A” by NA. Then, we can use the following R code:
vec_NA <- vec # Duplicate vector vec_NA[vec_NA == "A"] <- NA # Replace particular value with NA vec_NA # Print updated vector #  NA "B" NA "C" "B"
Have a look at the previous output: We have created a new character vector called vec_NA that contains Not Available values at the index positions where our input vector had the character value “A”.
Example 2: Replace Specific Character Value with NA in Data Frame
In this example, I’ll show how to replace characters in data frame variables by NA.
First, we have to create some example data:
data <- data.frame(x1 = letters[1:5], # Create example data frame x2 = letters[6:2], x3 = letters[3:7]) data # Print example data frame
As shown in Table 1, the previous R syntax has created a data frame with five rows and three columns. All the columns contain characters.
Now, we can replace a particular character value (i.e. “c”) with NA using a logical condition:
data_NA <- data # Duplicate data frame data_NA[data_NA == "c"] <- NA # Replace particular value with NA data_NA # Print updated data frame
In Table 2 it is shown that we have created a new data frame containing NA values using the previous R programming code.
Video & Further Resources
In case you need more info on the content of this article, you might want to watch the following video of my YouTube channel. I illustrate the topics of this article in the video:
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In addition, you may want to have a look at the other articles on my website. I have released several related tutorials on topics such as dplyr, merging, and missing data.
- na_if R Function of dplyr Package
- Merge Two Unequal Data Frames & Replace NA with 0
- Replace Last Comma of Character with &-Sign
- Replace NA with Last Observed Value
- R Programming Language
At this point you should have learned how to replace certain character strings with NA in the R programming language. Let me know in the comments section, in case you have additional questions. Furthermore, please subscribe to my email newsletter in order to receive updates on the newest articles.
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I have a question for you.
How to select all columns while we have many to replace “?” with “na”???
Does this code solve your question?
Thank you for your videos. How would to change NA by a character (like “No data” and only for a specific column (not in all data)?
Thank you in advance.
Thank you for your comment, glad you like my videos!
You may do something like this: