Change display order of factors for overlapping data

Question

I have a plot with overlapping points and would like to change which group will be on top.

Please check this example, I manage to invert a and b in terms of colour and order in the legend, with rev() but "b" is still on top of "a". Any solution?

Thanks in advance

D.

library(ggplot2)

mytable <- data.frame(x = rep(1:10, 2), 
          y = c(1:10, (1.1:10.1)),
          var = factor(c(rep("a",10), rep("b",10)))
          )

ggplot(mytable) +
  geom_point(aes(x=x,y=y, colour = var), cex=2)

mytable$var_rev <- with(mytable, factor(var, levels=rev(levels(var)))) 

ggplot(mytable) +
  geom_point(aes(x=x,y=y, colour = var_rev), cex=2)

Answer 1

Try this:

library(tidyverse)
mytable %>%
  arrange(desc(var)) %>%
  ggplot() +
  geom_point(aes(x=x,y=y, colour = var), cex=2)

Just:

ggplot(mytable) +
     geom_point(aes(x=x,y=y, colour = var), cex=2)

The points are plotted in the same order as in the data frame