How to create boxplot with multiple factor levels using ggplot2 in R?

To create a boxplot, we have one factor and one numerical column and the boxplot is created for each category or levels in that factor. Now if we have two factors then the boxplot can be created for both factor levels by passing fill argument in geom_boxplot. This will help us to differentiate between the boxplots for the two factors. Check out the below examples to understand how it works.

Example

Consider the below data frame −

Live Demo

> x<-sample(c("Male","Female"),30,replace=TRUE)
> y<-rnorm(30)
> grp<-sample(letters[1:3],30,replace=TRUE)
> df<-data.frame(x,y,grp)
> df

Output

       x              y  grp
1 Female    0.790349405    b
2   Male    0.868186299    b
3 Female   -2.108607808    b
4 Female    0.284872060    c
5   Male   -1.128470452    b
6   Male    0.001181183    b
7 Female   -2.915847134    c
8   Male   -1.416607857    c
9 Female   -1.784574028    a
10  Male    0.685830764    a
11 Female   0.581216168    c
12   Male   0.387109500    c
13 Female   0.611448059    c
14 Female   0.603614728    c
15   Male   0.207989975    c
16   Male   0.357018523    b
17 Female  -0.196608618    c
18   Male   1.165436068    c
19   Male   0.466733550    c
20 Female  -1.293515169    b
21   Male  -1.046339186    b
22 Female   1.692938740    c
23 Female   1.360998968    a
24 Female  -0.141122217    c
25   Male  -0.946920446    a
26 Female   1.091516275    c
27   Male   0.216101163    a
28 Female   0.935390544    a
29   Male  -0.636606941    a
30 Female   0.266238867    b

Loading ggplot2 and creating the boxplot −

> library(ggplot2)
> ggplot(df,aes(x,y))+geom_boxplot(aes(fill=grp))

Output