Reverse order of breaks in ggplot, ggridges

I have a dataset with Length (integer) and Year (factor) that I want to plot using ggridges. Here is an analogous dataset with integer and factor data. How do I change the order of Species (i.e. factor) on the y-axis?

library(ggplot2)
library(ggridges)
library(viridis)
library(datasets)

order <- c("setosa", "versicolor", "virginica")

ggplot(iris, aes(x = Sepal.Length, y = Species, fill = ..x..), order(Species)) + 
  geom_density_ridges_gradient(scale = 3, rel_min_height = 0.01) +
  scale_fill_viridis(name = "Sepal.Length", option = "A") +
  theme_ridges() +
  labs(title = 'Sepal Length distributions for irises')

Here, order(Species) or order(order) doesn't work.

I tried:

scale_y_reverse(breaks=order), expand = c(0.01, 0))

but then realized this is for continuous variables (tried with year as numeric - didn't work).

Is this what you want? I added mutate(Species = factor(Species, levels = rev(myorder))) to your code

library(dplyr)
library(ggplot2)
library(ggridges)
library(viridis)
library(datasets)

myorder <- c("setosa", "versicolor", "virginica")
iris <- iris %>% 
  mutate(Species = factor(Species, levels = rev(myorder)))

ggplot(iris, aes(x = Sepal.Length, y = Species, fill = ..x..), Species) + 
  geom_density_ridges_gradient(scale = 3, rel_min_height = 0.01) +
  scale_fill_viridis(name = "Sepal.Length", option = "A") +
  theme_ridges() +
  labs(title = 'Sepal Length distributions for irises')
#> Picking joint bandwidth of 0.181

Edit: another simpler way is to use fct_rev() from the forcats package

library(forcats)
library(ggplot2)
library(ggridges)

ggplot(iris, aes(x = Sepal.Length, y = fct_rev(Species), fill = ..x..), Species) + 
  geom_density_ridges_gradient(scale = 3, rel_min_height = 0.01) +
  scale_fill_viridis_c(name = "Sepal.Length", option = "A") +
  theme_ridges() +
  labs(title = 'Sepal Length distributions for irises')
#> Picking joint bandwidth of 0.181

^{Created on 2018-09-27 by the reprex package (v0.2.1.9000)}