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Question

I'm making some plots in ggplot with a colorbar legend like below. By default the legend has only 4 labels showing the value of specific colors. There are theme elements which can change the size of the colorbar, but not the number of labels. How can I increase the number of labels?

library(ggplot2)

ggplot(mtcars, aes(x=mpg, y=carb, color=disp)) + 
  geom_point(size=3) + 
  theme(legend.key.height = unit(2,'cm'))

Answer 1

You just need to specify the breaks in scale_color_continous()

g1 <- ggplot(mtcars, aes(x=mpg, y=carb, color=disp)) + 
  geom_point(size=3) + 
  theme(legend.key.height = unit(2,'cm'))

g1 + scale_color_continuous(breaks=seq(50,500,25))