GGplot reverse the boxplot sequence

Question

How can I reverse the order of Boxplot. In the picture you can see that 'After' is shown ahead of 'Before'. I want to reverse the order.

Answer 1

You can use fct_rev for reversing the order of a factor or fct_relevel for changing the order manually.

Here is an example df.

df <- data.frame(values = rnorm(n = 300, mean = 50, sd = 15),
                 time = factor(rep(c(30, 40, 50), 100)),
                 situation = rep(c("Before", "After"), each = 150))

And here a example codes for the problem.

library(ggplot2)
library(forcats)

ggplot(df) +
  geom_boxplot(aes(x = time, 
                   y = values, 
                   color = fct_rev(situation))) +
  guides(color = guide_legend(title = "situation"))


ggplot(df) +
  geom_boxplot(aes(x = time, 
                   y = values, 
                   color = fct_relevel(situation, "After", after = 1))) +
  guides(color = guide_legend(title = "situation"))

Both codes result in this plot.