The package has a list of default colors that it uses for the elements in a plot depending on the number of total elements.

For example, the following code shows how to create a bar plot with three bars:

library(ggplot2)

#create data frame
df <- data.frame(team=c('A', 'B', 'C'),
                 points=c(22, 28, 15))

#create bar plot using df
ggplot(df, aes(x=team, y=points, fill=team)) +
  geom_bar(stat = "identity")

By default, ggplot2 chooses to use a specific shade of red, green, and blue for the bars.

We can use the hue_pal() from the scales package to extract the actual hex color codes used in the plot:

library(scales)

#extract hex color codes for a plot with three elements in ggplot2 
hex <- hue_pal()(3)

#display hex color codes
hex

[1] "#F8766D" "#00BA38" "#619CFF"

Here’s how to interpret the output:

• The hex color code for the red in the plot is #F8766D.
• The hex color code for the green in the plot is #00BA38.
• The hex color code for the blue in the plot is #619CFF.

We can use also use show_col() from the scales package to overlay the hex color codes on their actual colors:

library(scales)

#extract hex color codes for a plot with three elements in ggplot2 
hex <- hue_pal()(3)

#overlay hex color codes on actual colors
show_col(hex)

And we can use the following code to create a plot that shows the default ggplot2 colors for plots with one through eight elements:

library(scales)

#set margins of plot area
par(mai = c(0.1, 0, 0.1, 0), bg = "grey85")

#create plot with ggplot2 default colors from 1 to 8
gc.grid <- layout(matrix(1:8, nrow = 8))
for(i in 1:8){
   gc.ramp <- hue_pal()(i)
   plot(c(0, 8), c(0,1),
        type = "n", 
        bty="n", 
        xaxt="n", 
        yaxt="n", xlab="", ylab="")
   for(j in 1:i){
      rect(j - 1, 0, j - 0.25, 1, col = gc.ramp[j])
   }
}

And we can use the following code to display the hex color codes for each color shown in the plot:

library(scales)

#display ggplot2 default hex color codes from 1 to 8
for(i in 1:8){
  print(hue_pal()(i))
}

[1] "#F8766D"
[1] "#F8766D" "#00BFC4"
[1] "#F8766D" "#00BA38" "#619CFF"
[1] "#F8766D" "#7CAE00" "#00BFC4" "#C77CFF"
[1] "#F8766D" "#A3A500" "#00BF7D" "#00B0F6" "#E76BF3"
[1] "#F8766D" "#B79F00" "#00BA38" "#00BFC4" "#619CFF" "#F564E3"
[1] "#F8766D" "#C49A00" "#53B400" "#00C094" "#00B6EB" "#A58AFF" "#FB61D7"
[1] "#F8766D" "#CD9600" "#7CAE00" "#00BE67" "#00BFC4" "#00A9FF" "#C77CFF" "#FF61CC"

Additional Resources