How to Use a Transparent Background in ggplot2

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You can use the following syntax to create a transparent background in a plot in ggplot2:

p +
  theme(
    panel.background = element_rect(fill='transparent'), #transparent panel bg
    plot.background = element_rect(fill='transparent', color=NA), #transparent plot bg
    panel.grid.major = element_blank(), #remove major gridlines
    panel.grid.minor = element_blank(), #remove minor gridlines
    legend.background = element_rect(fill='transparent'), #transparent legend bg
    legend.box.background = element_rect(fill='transparent') #transparent legend panel
  )

If you decide to export the plot using ggsave(), be sure to specify that the background should be transparent:

ggsave('myplot.png', p, bg='transparent')

The following example shows how to use this syntax in practice.

Example: Use a Transparent Background in ggplot2

The following code shows how to create a simple grouped boxplot in ggplot2:

library(ggplot2) 

#make this example reproducible
set.seed(1)

#create dataset
data frame(team=rep(c('A', 'B', 'C'), each=50),
                   program=rep(c('low', 'high'), each=25),
                   values=seq(1:150)+sample(1:100, 150, replace=TRUE))

#create boxplot
ggplot(data, aes(x=team, y=values, fill=program)) + 
  geom_boxplot()

We can use the following code to create a transparent background for the plot:

library(ggplot2) 

#make this example reproducible
set.seed(1)

#create dataset
data frame(team=rep(c('A', 'B', 'C'), each=50),
                   program=rep(c('low', 'high'), each=25),
                   values=seq(1:150)+sample(1:100, 150, replace=TRUE))

#create boxplot
p aes(x=team, y=values, fill=program)) + 
       geom_boxplot() +
       theme(
         panel.background = element_rect(fill='transparent'),
         plot.background = element_rect(fill='transparent', color=NA),
         panel.grid.major = element_blank(),
         panel.grid.minor = element_blank(),
         legend.background = element_rect(fill='transparent'),
         legend.box.background = element_rect(fill='transparent')
       )

#display boxplot
p

We can then export this plot to a PNG file, specifying that the background should be transparent in the exported image:

ggsave('grouped_boxplot.png', p, bg='transparent')

If I open this exported file on my computer, I can see that the background is indeed transparent:

Additional Resources

How to Change Font Size in ggplot2
How to Remove a Legend in ggplot2
How to Remove Gridlines in ggplot2