Display Legend on Top Using ggplot2 in R

To display legend on top using ggplot2 in R, we can use theme function with legend.justification argument to top.

For Example, if we have a data frame called df that contains three columns say X and Y and F where X and Y are numerical and F is categorical then we can create scatterplot between X and Y with point colored by values in F by using the command given below −

ggplot(df,aes(X,Y))+geom_point(aes(colour=factor(F)))+theme(legend.justification="top")

Example

Following snippet creates a sample data frame −

x<-rnorm(20)
y<-rnorm(20)
Grp<-sample(LETTERS[1:3],20,replace=TRUE)
df<-data.frame(x,y,Grp)
df

The following dataframe is created

           x             y  Grp
 1 -1.066129589  0.828709138 C
 2 -1.222825364 -0.306424935 C
 3  0.429354500 -1.446665340 B
 4 -0.609955977 -0.288351976 A
 5  1.200129675  0.716336213 C
 6  0.800850596 -1.095220235 C
 7  0.517368694  1.561305370 C
 8 -0.006456066 -0.002988512 B
 9  0.555280469 -1.241763197 C
10 -2.043538292 -1.734706075 C
11 -1.151771052 -0.878394321 B
12  0.845068460 -1.139618835 C
13  2.071684310  0.825474682 B
14 -0.250229200 -0.120597321 B
15 -1.280790787 -0.461785183 A
16 -0.028062183 -0.154095381 B
17 -0.620917924  0.398107075 A
18  0.302128850  0.497374731 C
19  0.719935519 -1.230463223 A
20 -0.862276767  0.518153886 A

To load ggplot2 package and create scatterplot between x and y colored based on Grp values on the above created data frame, add the following code to the above snippet −

x<-rnorm(20)
y<-rnorm(20)
Grp<-sample(LETTERS[1:3],20,replace=TRUE)
df<-data.frame(x,y,Grp)
library(ggplot2)
ggplot(df,aes(x,y))+geom_point(aes(colour=factor(Grp)))

Output

If you execute all the above given snippets as a single program, it generates the following Output −

To create scatterplot between x and y colored based on Grp values with legend on top on the above created data frame, add the following code to the above snippet −

x<-rnorm(20)
y<-rnorm(20)
Grp<-sample(LETTERS[1:3],20,replace=TRUE)
df<-data.frame(x,y,Grp)
library(ggplot2)
ggplot(df,aes(x,y))+geom_point(aes(colour=factor(Grp)))+theme(legend.justification="top")

Output

If you execute all the above given snippets as a single program, it generates the following Output −