How to Fix the Error: Mapping Must be Created by aes() in GGPLOT2

“Error: mapping must be created by aes()” is an error you would eventually run into if you frequently use GGPLOT2 to create graphs in R. The last time I ran into this error was when I was creating profile plots using geom_line(). I succeeded to recreate the error using the R codes below.

Visit this page if you would like to understand the dataset used in this post. We will immediately go into fixing the error. I was able to fix the error with any one of the following four methods:

1. Place the aes() and data= arguments in the ggplot call

Place the aes() and data= arguments in the ggplot() instead of the geom_() function.

#try doing this:
ggplot(statsBG, aes(x=timedays, y=meanBG, color=groupid)) +
  geom_line()

#instead of this:
ggplot() +
  geom_line(statsBG, aes(x=timedays, y=meanBG, color=groupid))

2. Use the mapping= syntax

Try using the mapping= syntax as shown below

#use the mapping= syntax
ggplot() +
  geom_line(statsBG, mapping=aes(x=timedays, y=meanBG, color=groupid))

C. Use the data= syntax

Try using the data= syntax for the dataset argument.

#use the data= syntax
ggplot() +
  geom_line(data=statsBG, aes(x=timedays, y=meanBG, color=groupid))

D. Specify aes() first

#specify aes() first before the dataset argument
ggplot() +
  geom_line(aes(x=timedays, y=meanBG, color=groupid), statsBG)

We hope you were able to fix your error with one of the above methods. If you have any tips or comments, please leave them in the comment field below.