How to remove the boxes around legend of a plot created by ggplot2 in R?

When we create a plot with legend using ggplot2, the legend values are covered with a box and that makes an impact on the smoothness of the plot. These boxes around the legend values can be removed so that complete the chart becomes more appealing to the viewer and it can be done with the help of theme function by setting the legend.key element to blank.

Example

Consider the below data frame −

set.seed(1)
x<-rnorm(20)
y<-rpois(20,2)
Group<-rep(c("A","B","C","D"),times=5)
df<-data.frame(x,y,Group)
df

Output

  x    y    Group
1   -0.62645381 3 A
2   0.18364332 2 B
3  -0.83562861 3 C
4   1.59528080 2 D
5   0.32950777 2 A
6  -0.82046838 3 B
7   0.48742905 0 C
8   0.73832471 2 D
9   0.57578135 3 A
10 -0.30538839 3 B
11  1.51178117 2 C
12  0.38984324 4 D
13 -0.62124058 2 A
14 -2.21469989 1 B
15  1.12493092 0 C
16 -0.04493361 0 D
17 -0.01619026 1 A
18  0.94383621 2 B
19  0.82122120 2 C
20  0.59390132 2 D
> library(ggplot2)

Creating the scatter plot with different colors of groups −

ggplot(df,aes(x,y,color=Group))+geom_point()

Output

Here, we are getting legend colors in boxes. If we want to get rid of these boxes then we can use theme function as shown below −

ggplot(df,aes(x,y,color=Group))+geom_point()+theme(legend.key=element_blank())

Output