How to reorder the items in a legend?

Question

I\'m trying to change the order in which legend items appear. I\'ve spent about an hour at this, with no results.

Here\'s an example setup:

library(         


        

Answer 1

The order of legend labels can be manipulated by reordering and changing values in column a to the factor: d$a <- factor(d$a, levels = d$a)

So your code would look like this

library(ggplot2)
set.seed(0)
d <- data.frame(x = runif(3), y = runif(3), a = c('1', '3', '10'))

d$a <- factor(d$a, levels = d$a)

ggplot(d, aes(x = x, y = y)) + 
  geom_point(size=7, aes(color = a))

And the ouptut

Note, than now in legend: 1 is red, 3 is green and 10 is blue color