# R ggplot2 geom_path Error in FUN(X[[i]], …) object not found (2 Examples)

In this tutorial, I’ll explain how to reproduce and debug the “Error in FUN(X[[i]], …) : object not found” when using the geom_path function of the ggplot2 package in R programming.

The tutorial will consist of the following contents:

Here’s how to do it:

## Example Data, Add-On Packages & Default Plot

The following data will be used as a basis for this R programming tutorial:

```data <- data.frame(x = 1:6,                     # Create example data frame
y = 1:3,
group = rep(letters[1:3], each = 2))
data                                            # Print example data frame``` Table 1 visualizes the structure of our example data: It is composed of six rows and three columns.

We also need to install and load the ggplot2 package, to be able to use the corresponding functions.

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

Now, we can draw a ggplot2 plot of our data as follows:

```ggp <- ggplot(data,                             # Create ggplot2 plot without path
aes(x = x,
y = y,
col = group)) +
geom_point()
ggp                                             # Draw ggplot2 plot without path``` By executing the previous R programming syntax, we have plotted Figure 1, i.e. a ggplot2 scatterplot without a path.

Let’s specify the x- and y-axis coordinates for our path:

```data_path <- data.frame(x_path = c(1, 3, 5),    # Specify data for path
y_path = c(3, 2, 3))
data_path                                       # Print data for path``` As shown in Table 2, the previous R code has created a new data set called data_path, which contains all the coordinates of our path.

Next, we would like to add this path on top of our plot using the geom_path function. However, this can lead to problems…

## Example 1: Reproduce the Error in FUN(X[[i]], …) : object ‘group’ not found

In this example, I’ll show how to replicate the “Error in FUN(X[[i]], …) : object not found”.

Let’s assume that we want to add a path to our plot using the geom_path function. Then, we might try to do this as shown below:

```ggp +                                           # Trying to draw path
geom_path(data = data_path,
aes(x = x_path,
y = y_path))

As you can see, the previous R code has returned the error message “Error in FUN(X[[i]], …) : object ‘group’ not found”. This is because the geom_path function searches for the group variable in our path data set.

Let’s solve this issue!

## Example 2: Fix the Error in FUN(X[[i]], …) : object ‘group’ not found

In this example, I’ll show how to debug the “Error in FUN(X[[i]], …) : object not found”.

To accomplish this, we have to set the inherit.aes argument within the geom_path function to FALSE.

Consider the R syntax below:

```ggp +                                           # Drawing path properly
geom_path(data = data_path,
aes(x = x_path,
y = y_path),
inherit.aes = FALSE)``` As shown in Figure 2, we have plotted a ggplot2 scatterplot with a path on top. No error messages are shown anymore.

## Video & Further Resources

Have a look at the following video which I have published on my YouTube channel. In this tutorial, I give a detailed introduction to the ggplot2 Package and data visualization in R, structured in different sections with examples for beginners but also advanced users.

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Furthermore, you may have a look at some of the other posts on this website. Please find a selection of posts below.

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• trilisser
March 29, 2023 8:26 am

Thank you so much! That sh*t has really pissed me off.

• March 31, 2023 8:25 am