ggplot2 Error in R: Cannot use `+.gg()` with a single argument – new line?

In this R tutorial you’ll learn how to deal with the error “Cannot use `+.gg()` with a single argument”.

The tutorial consists of this information:

Let’s get started!

Example Data, Packages & Basic Graphic

As a first step, I have to construct some example data:

data <- data.frame(x1 = 1:5,    # Create example data
                   x2 = 1:5)
data                            # Print example data
#   x1 x2
# 1  1  1
# 2  2  2
# 3  3  3
# 4  4  4
# 5  5  5

The previously shown output of the RStudio console shows that our example data has five rows and two numeric variables.

For the examples of this tutorial, we’ll also need to install and load the ggplot2 package:

install.packages("ggplot2")     # Install & load ggplot2 package
library("ggplot2")

Now, we can move on to the examples…

Example 1: Reproduce the Error: Cannot use `+.gg()` with a single argument.

The following R programming code illustrates how to replicate the error:

Error: Cannot use `+.gg()` with a single argument. Did you accidentally put + on a new line?
Run `rlang::last_error()` to see where the error occurred.

Have a look at the following R code:

ggplot(data, aes(x1, x2))       # Create error message
+  geom_point()
# Error: Cannot use `+.gg()` with a single argument. Did you accidentally put + on a new line?
# Run `rlang::last_error()` to see where the error occurred.

As you can see, the RStudio console has returned the error message “Cannot use `+.gg()` with a single argument”.

The reason for this is that we have specified the + sign at the wrong position of our R syntax.

Next, I’ll explain how to solve this problem…

Example 2: Fix the Error: Cannot use `+.gg()` with a single argument.

In this example, I’ll explain how to handle the ggplot2 error “Cannot use `+.gg()` with a single argument” in R.

Consider the following R code:

ggplot(data, aes(x1, x2)) +     # Properly create ggplot2 plot
  geom_point()

The output of the previous R code is shown in Figure 1 – A scatterplot created with the ggplot2 package. No error messages occurred.

Have a closer look at the previous R code. As you might already have noticed, we have moved the + sign at the end of the first line of code instead of the beginning of the second line of code.

Video, Further Resources & Summary

Some time ago I have published a video on my YouTube channel, which shows the R code of this article. You can find the video below.

In addition, you may want to have a look at the other articles that I have published on this website:

• Fixing Error & Warning Messages in R
• Drawing Plots in R
• R Programming Examples

At this point you should know how to avoid the error message “Cannot use `+.gg()` with a single argument” in R programming. In case you have further questions, don’t hesitate to let me know in the comments section.