How to Fix Error: `data` must be a data frame, or other object coercible by `fortify()`, not a numeric vector

One error you may encounter in R is:

Error: `data` must be a data frame, or other object coercible by `fortify()`,
        not a numeric vector

This error occurs when you attempt to use ggplot2 to plot variables in a data frame, but you reference a vector instead of a data frame for the data argument.

This tutorial shares exactly how to fix this error.

How to Reproduce the Error

Suppose we have the following data frame in R:

#create data frame
df <- data.frame(x=c(1, 2, 3, 4, 5, 6, 7, 8),
                 y=c(4, 8, 14, 19, 14, 13, 9, 9))

#view data frame
df

  x  y
1 1  4
2 2  8
3 3 14
4 4 19
5 5 14
6 6 13
7 7  9
8 8  9

Now suppose we attempt to create a scatter plot to visualize the x and y variables within the data frame:

library(ggplot2)

#attempt to create scatter plot
ggplot(df$x, aes(x=x, y=y)) +
    geom_point()

Error: `data` must be a data frame, or other object coercible by `fortify()`,
        not a numeric vector

We receive an error because we referenced a numeric vector (df$x) within the data argument of the ggplot() function instead of a data frame.

How to Fix the Error

The way to fix this error is to reference a data frame for the data argument within the ggplot() function.

In our example, we should use df instead of df$x for the data argument:

library(ggplot2)

#create scatter plot
ggplot(df, aes(x=x, y=y)) +
    geom_point()

Notice that we’re able to create the scatter plot successfully without any error this time.

Additional Resources

The following tutorials explain how to troubleshoot other common errors in R:

How to Fix: ggplot2 doesn’t know how to deal with data of class uneval
How to Fix: Error in stripchart.default(x1, …) : invalid plotting method
How to Fix: Error in eval(predvars, data, env) : object ‘x’ not found