R ggplot2 Error: Aesthetics must be either length 1 or the same as the data

 

In this tutorial you’ll learn how to fix the error message “Aesthetics must be either length 1 or the same as the data” in the R programming language.

Table of contents:

Let’s start right away…

 

Example Data, Add-On Packages & Default Graph

As a first step, we’ll need to create some data that we can use in the examples later on:

data <- data.frame(x = LETTERS[1:5],    # Create example data
                   y = 1:5)
data                                    # Print example data
#   x y
# 1 A 1
# 2 B 2
# 3 C 3
# 4 D 4
# 5 E 5

In case we want to draw our data with the ggplot2 package, we also have to install and load ggplot2 to R:

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

 

Example 1: Reproducing the Error: Aesthetics must be either length 1 or the same as the data

In Example 1, I’ll show how to replicate the error message “Aesthetics must be either length 1 or the same as the data” in R.

Have a look at the following R code:

ggplot(data, aes(x, y, fill = c("red", "blue"))) + # Try to draw ggplot2 plot
  geom_bar(stat = "identity")
# Error: Aesthetics must be either length 1 or the same as the data (5): fill

As you can see, the RStudio console returns the error “”Aesthetics must be either length 1 or the same as the data”.

The reason for this is that we have specified the fill argument within the aes function to be equal a vector of length 2 (i.e. c(“red”, “blue”)).

However, our example data has five categories and therefore doesn’t know which filling color should be used for which category.

Let’s solve this problem!

 

Example 2: Fixing the Error: Aesthetics must be either length 1 or the same as the data

This example shows how to deal with the ggplot2 error “Aesthetics must be either length 1 or the same as the data”.

As discussed before, we have to specify a filling color for each group in our data. The easiest way to do this is that we set fill to be equal to our grouping variable (i.e. x):

ggplot(data, aes(x, y, fill = x)) +     # Properly drawing ggplot2 plot
  geom_bar(stat = "identity")

 

r graph figure 1 error aesthetics must be length 1 or same as data r

 

As illustrated in Figure 1, the previous syntax created a ggplot2 barplot in R. Looks good!

 

Video & Further Resources

I have recently released a video on my YouTube channel, which shows the R programming syntax of this tutorial. Please find the video below:

 

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Furthermore, I can recommend to have a look at the other articles of my homepage.

 

Summary: You learned in this article how to handle the error “Aesthetics must be either length 1 or the same as the data” in R programming. In case you have any further questions, let me know in the comments.

 

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4 Comments. Leave new

  • Ananya Sharma
    January 10, 2022 5:14 pm

    Hi,
    I was trying to do the following code, and it hasn’t worked out.
    Could you please help me know, where I went wrong:
    I have picked the inbuilt set mpg and also run the suitable packages.
    I get the error: Error: Aesthetics must be either length 1 or the same as the data (234): x, y and fill

    set.seed(10)
    names<-c(rep("A",20),
    rep("B",5),
    rep("C",30),
    rep("D",100))
    value<- c(sample(2:5, 20, replace=T),
    sample(4:10, 5, replace=T),
    sample(1:7, 30, replace=T),
    sample(3:8, 100 ,replace=T))

    data1<-data.frame(names,value)
    data1
    ggplot(data=mpg,(aes(x=names,y=value,fill=names))) +
    geom_boxplot( stat="identity")

    Thanks and kind regards,
    Ananya

    Reply
    • Hey Ananya,

      Your code works for me when I do the following changes:

      • Replace mpg by data1
      • Delete stat=”identity”

      My final code looks like this:

      ggplot(data=data1,(aes(x=names,y=value,fill=names))) +
        geom_boxplot()

      And the resulting plot looks like this:

       

      ggplot2 boxplot

       

      Regards,
      Joachim

      Reply
  • CHD <- rawdata$anychd
    CHD2 <- as.character(CHD)
    prev_CHD <- factor(CHD2, levels = c(0,1), labels = c("NO", "YES"))
    age <- rawdata$AGE

    ggplot(rawdata, aes(x=prev_CHD, y=age, coll = prev_CHD)) + geom_boxplot() + theme(legend.position = "none") + xlab("CHD Event") +ylab("Age (years)") + ggtitle("Relationship Between Age & Presence of CHD Event")

    I also get the same error and was wondeirng why? Thanks!

    Reply
    • Hey Charlotte,

      You should store all the relevant information for the plot within a single data frame, not in separate data objects.

      You may create a data frame containing prev_CHD and age and run the code again based on this data frame.

      Regards,
      Joachim

      Reply

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