Pass Data Frame Column Name to Function in R (Example)

In this R tutorial you’ll learn how to use variable names in manually created functions.

Table of contents:

• Creating Example Data
• Example: Use Variable Names in User-Defined R Function
• Video, Further Resources & Summary

Let’s dive right in:

Creating Example Data

First, we need to create some example data that we can use in the tutorial later on:

my_data <- data.frame(x1 = 1:5,                          # Create example data
                      x2 = LETTERS[1:5],
                      x3 = 1)
my_data                                                  # Return data to RStudio console
#   x1 x2 x3
# 1  1  A  1
# 2  2  B  1
# 3  3  C  1
# 4  4  D  1
# 5  5  E  1

The previous R code created a data frame with five rows and three variables x1, x2, and x3. Now, let’s create a user-defined function, which uses these columns…

Example: Use Variable Names in User-Defined R Function

The following R syntax creates a user-defined function in R. Note that we are defining data_input and columns as input arguments for the function.

my_fun <- function(data_input, columns) {                # Write user-defined function
  data_output <- data_input[ , columns]
  # At this point of the function, do with the columns whatever you want...
  return(data_output)
}

Now, we can apply the function by specifying our example data as data_input and the variable names we want to use as columns:

my_fun(data_input = my_data, columns = c("x1", "x3"))    # Apply user-defined function
#   x1 x3
# 1  1  1
# 2  2  1
# 3  3  1
# 4  4  1
# 5  5  1

As you can see, our function just returns the two specified column names. However, you may do whatever you want within your own user-written function.

Video, Further Resources & Summary

Would you like to know more about manually created functions in R? Then you may want to have a look at the following video of my YouTube channel. In the video, I show the R code of this article in a programming session:

The YouTube video will be added soon.

In addition, you may read some of the related tutorials of https://statisticsglobe.com/. You can find a selection of tutorials here.

• R Functions List (+ Examples)
• The R Programming Language

Summary: In this R programming tutorial you learned how to pass column names as argument to a manual function. Let me know in the comments section, in case you have further questions.