You can use the following syntax to remove a legend title from a plot in ggplot2:
ggplot(df, aes(x=x_var, y=y_var, color=group_var)) +
geom_point() +
labs(color=NULL)
The argument color=NULL in the labs() function tells ggplot2 not to display any legend title.
The following example shows how to use this syntax in practice.
Example: Remove Legend Title from Plot in ggplot2
Suppose we have the following data frame in R that contains information about various basketball players:
df frame(assists=c(3, 4, 4, 3, 1, 5, 6, 7, 9),
points=c(14, 8, 8, 16, 3, 7, 17, 22, 26),
position=rep(c('Guard', 'Forward', 'Center'), times=3))
#view data frame
df
assists points position
1 3 14 Guard
2 4 8 Forward
3 4 8 Center
4 3 16 Guard
5 1 3 Forward
6 5 7 Center
7 6 17 Guard
8 7 22 Forward
9 9 26 Center
If we use geom_point() to create a scatterplot in ggplot2, a legend will be shown with a title by default:
library(ggplot2) #create scatter plot of assists vs. points, grouped by position ggplot(df, aes(x=assists, y=points, color=position)) + geom_point(size=3)
Notice that the legend currently has the text “position” shown as the legend title.
To remove this title from the legend, we can use the labs(color=NULL) argument:
library(ggplot2) #create scatter plot and remove legend title ggplot(df, aes(x=assists, y=points, color=position)) + geom_point(size=3) + labs(color=NULL)
Notice that the legend title has been removed.
Additional Resources
The following tutorials explain how to perform other common tasks in ggplot2:
How to Change the Legend Title in ggplot2
How to Change Legend Size in ggplot2
How to Change Legend Position in ggplot2